(All Gens) Mechanical Differences Between the Gens

[Jellicent*]

Alright, so, I'm making a letter detailing the major mechanical changes that occurred between each generation, so current gen players can pick up on key differences and have an easier time learning past gens. Similarly, past gen players could check it out in reverse to learn up on how the game's mechanics have changed over time should they wish to learn BW. Stuff like a move's Base Power, accuracy, or a slight change in how an ability works probably won't be included, though competitively relevant move mechanics (RBY Hyper Beam, BW Explosion nerf, etc.) should be listed. I'm compiling this mostly from memory, so I'm sure I'll be missing shit, which is where you all come in. Let's try to fill in any cracks here to make this as all-encompassing as possible~

Changes from BW to DPP

• A Pokemon's sleep counter does not reset when switching out. Also, sleep lasts for 1 to 4 turns rather than BW's 1 to 3.
• The moves Explosion and SelfDestruct temporarily halves the opponent's Defense, effectively doubling their Base Power.
• Wish heals the target by 50% of its HP, rather than 50% of the user's HP.
• The trapping effects of Mean Look can be Baton Passed.
• Taunt lasts for 2 to 4 turns.
• Encore lasts for 3 to 7 turns.

Changes from DPP to ADV

• All Dark, Dragon, Electric, Fire, Grass, Ice, Psychic, and Water moves are special moves. All Bug, Fighting, Flying, Ghost, Ground, Normal, Poison, Rock, and Steel moves are physical moves.
• Sleep lasts for 1 to 6 turns.
• When the faster Pokemon faints, the opposing Pokemon does not get to move.
• Taunt only lasts for 2 turns.
• Encore lasts for 2 to 6 turns.
• Counter and Mirror Coat treat Hidden Power as physical, regardless of type.

Changes from ADV to GSC

• IVs range from 0-15 rather than 0-31.
• A Pokemon can have 255 EVs in every stat.
• Natures and Abilities do not exist.
• If a badly poisoned Pokemon is switched out, it will be afflicted with regular poisoning.
• If a burned or poisoned Pokemon KOes its opponent, it will not take burn or poison damage that turn.
• A frozen Pokemon cannot attack on the turn it thaws out.
• If Sleep Talk chooses Rest, the Pokemon will regain all of its health and have its sleep counter reset. If Sleep Talk chooses Roar or Whirlwind and the user is faster than the opponent, it will fail.
• Phazing moves, Counter, and Vital Throw must go second in order to succeed.
• Only one layer of Spikes can be set.

Changes from GSC to RBY

• Rather than Special Attack and Special Defense stats, Pokemon simply have a Special stat that functions as both.
• Items do not exist.
• Sleep lasts for 0 to 6 turns. Also, a Pokemon cannot attack on the turn it wakes up. A Pokemon using Rest will wake up after 2 turns rather than 3.
• If a Pokemon uses Rest while burned or paralyzed, it will retain the respective Attack or Speed drop until switching out. If a Pokemon uses an Attack or Speed boosting move while burned or paralyzed, respectively, the drops will be removed and the stat will raise as if no status was inflicted.
• The probability of critical hits is determined by base Speed. The formula used is %CH = Base Speed x 100/512. Critical hits ignore all stat changes for both Pokemon, as well as the effects of Light Screen and Reflect.
• Bug is super effective against Poison and has normal effectiveness against Ghost, Poison is super effective against Bug, Ghost has no effect against Psychic, and Ice has normal effectiveness against Fire.
• If a Pokemon KOes an opposing Pokemon or breaks a Substitute with Hyper Beam, it does not have to recharge the next turn.
• A frozen Pokemon will not randomly thaw out.
• The accuracy and critical hit rate of all moves is reduced by 0.4% (except Swift, which will never miss).
• A poisoned or burned Pokemon loses 1/16 of its health rather than 1/8. Similarly, Leech Seed drains 1/16 of health rather than 1/8.
• A Pokemon hit by a partial trapping move cannot attack for the duration of the attack. However, it can switch out of the partial trapping move.
• Steel and Dark do not exist as types.
• Night Shade and Seismic Toss hit everything, regardless of type.
• If Explosion or SelfDestruct is used against a Pokemon behind a Substitute and breaks the Substitute, the user will not faint.
• Roar and Whirlwind have no effect.
• Haze removes major status conditions from the opponent.
• Horn Drill, Fissure, and Guillotine will always fail if the opposing Pokemon has higher Speed.

[Golden Gyarados]

Originally Posted by Fat Jellicent

Changes from GSC to RBY

• Rather than Special Attack and Special Defense stats, Pokemon simply have a Special stat that functions as both.
• Items do not exist.
• Sleep lasts for 1 to 7 turns. Also, a Pokemon cannot attack on the turn it wakes up. A Pokemon using Rest will wake up after 2 turns rather than 3.
• The probability of critical hits is determined by Speed.
• Bug is super effective against Poison and has normal effectiveness against Ghost, Poison is super effective against Bug, Ghost is not very effective against Psychic, and Ice has normal effectiveness against Fire.
• If a Pokemon KOes an opposing Pokemon with Hyper Beam, it does not have to recharge the next turn.
• A frozen Pokemon will not randomly thaw out.
• A poisoned or burned Pokemon loses 1/16 of its health rather than 1/8.
• A Pokemon hit by a partial trapping move cannot attack for the duration of the attack.
• Steel and Dark do not exist as types.

It would be good to clarify that critical hits are based on *base* speed, and not actual speed (ie, critical hit chances aren't affected by speed boosts or drops) - that's something people get confused about a lot.

Also, in Gen I, Psychic is actually immune to Ghost, rather than not very effective as you state.

EDIT: In Gen I, when you rest off a burn or paralysis, you maintain the attack and speed drops, respectively, until you switch out. Is that true in later gens?

[Crystal_]

I wrote this around 2 years ago. It's on the PO wiki but whatever

RBY mechanics

---

== Important RBY differences ==


===== Main differences =====

RBY battling mechanics are very different from future generations. Here is a list of the differences you will experience when playing RBY.

*Pokémon from number 152 onward do not exist.
*Moves created in later generations do not exist.
*EVs can maximize all stats in 63 points in the level 100 stat formula, rather than two.
*IVs go from 0 to 15, rather than from 0 to 31, but the IV is multiplied by two in the stat formula.
*Natures do not exist.
*Abilities do not exist.
*Items do not exist.
*Genders do not exist.
*Special Attack and Special Defense are combined in one Special stat. Therefore, moves that alter Special will increase/decrease both Special Defense and Special Attack simultaneously (Amnesia, Growth, and Psychic).


===== Effectiveness and types =====

*Ice is neutral against Fire rather than not very effective.
*Bug is super effective against Poison, rather than neutral.
*Poison is super effective against Bug, rather than not very effective.
*Ghost is worthless against Psychic, rather than super effective.
*Dark and Steel types do not exist.
*The only Dragon-type move is Dragon Rage, which always takes 40 HP to the opponent regardless of its type.


===== 1:256 error =====

The accuracy and critical hit rates of every move (besides Swift, which has "--" accuracy) are reduced by 0.4% (0'0390625%) due to a hexadecimal 255:256 error. This means that a 100% accurate move, such as Body Slam or Thunder Wave, will hit 99.6% (99.609375%) of the time.


===== Critical hits =====

The chance of getting a Critical Hit (CH) in RBY is calculated through this formula: '''''%CH = Base Speed x 100/512'''''.
High-CH ratio moves use a formula with 64 in place of 512 ('''''%CH = Base Speed x 100/64'''''). Critical Hit chances are capped at 100% and the 1:256 error applies, so the %CH you get using this formula has to be multiplied by 255/256, and, therefore, a fast Pokémon with a High-CH move (such as Persian's Slash) will have no more than a 99.6% chance to score a Critical Hit.

Critical Hits ignore all stat changes from both Pokémon, including Reflect, Light Screen, and the user's boosts.


===== One-Hit KO moves =====

Horn Drill, Fissure and Guillotine will always fail if the opposing Pokémon's actual speed is higher than yours. If not, their accuracy is 30%, like in later generations.


===== Partial trapping moves =====

Wrap, Fire Spin, Clamp, and Bind prevent both Pokémon attack while the move is active. In addition, the resulting damage each turn is not 1/16% HP (as in other generations), as the damage formula is applied each turn using the power of the move (and being able to CH etc.). However, the accuracy is only applied in the first move of the 2-5 hits.

Partial Trapping Moves do not actually trap in RBY, as the trapped Pokémon can switch out. The PT move is immediately used again on the Pokémon that switches in. Move PP is also unlimited for PT moves due to an error.

Like in later generations, these moves last 2-5 turns; with a 37'5% to last 2-3, and a 12'5% chance to last 4-5 turns.


===== Stat boosts and drops =====

Attack boosting moves (Swords Dance, Sharpen, Meditate) will negate the attack reduction from Burn and will increase attack as if the burn had never occurred. Switching out and back in returns the attack reduction.

Likewise, Speed boosting moves (Agility) will negate the speed reduction from Paralysis and will increase the speed as if the paralysis had never occurred. The Pokémon can still Fully Paralyze. Switching out and back in returns the speed reduction.

Using Rest removes the status, but the speed/attack reduction is not removed until the Pokémon switches out and back in again or until an attack/speed boosting move is used.


===== Sleep =====

Sleep lasts from 0 to 7 turns, but a Pokémon is unable to move the turn it wakes up.


===== Freeze =====

A frozen Pokémon will only be defrosted if is hit with a fire-type move or the move Haze is used.


===== Physical and Special moves =====

*Bug, Fighting, Flying, Ground, Ghost, Normal, Poison and Rock-type moves are physical (Attack and Defense applied).
*Electric, Fire, Grass, Ice, Psychic and Water-type moves are special (Special stat of each Pokémon applied).


===== Moves with important differences =====

*'''Agility''': See Stat boosts and drops.
*'''Amnesia''': See Special.
*'''Bind''': See Partial-trapping moves.
*'''Blizzard''': Its accuracy is 90%.
*'''Clamp''': See Partial-trapping moves.
*'''Counter''': Can only be used to double back the damage done from a Normal or Fighting-type move (including Seismic Toss and Counter itself). Counter always goes second. Counter is not reset (and thus can be used multiple times) until the user switches out or the foe uses PP. Ghosts are immune (even to a counter that is based off of Seismic Toss). Counter will not counter damage done to the user's substitute.
*'''Double-Edge''': Its base power is 100.
*'''Explosion''': Its base power is 170 (340 after defense is halved). If it is used against a Substitute and breaks it, the user will not faint.
*'''Fire Spin''': See Partial-trapping moves.
*'''Fissure''': See One-Hit KO Moves.
*'''Focus Energy''': Is glitched in RBY, and will lower the user's CH ratio instead of increasing it.
*'''Growth''': See SPECIAL STAT.
*'''Guillotine''': See One-Hit KO moves.
*'''Horn Drill''': See One-Hit KO moves.
*'''Hyper Beam''': If it OHKOs the opponent or breaks a Substitute, it will not need a recharge turn.
*'''Leech Seed''': 1/16 of the enemy's HP is taken, instead of 1/8 like in later generations. Grasses are immune.
*'''Light Screen''': Its effect will disappear if the user is switched out, but if you do not, the effect will remain active until the user faints.
*'''Psychic''': Has a 30% chance to lower the Special stat one stage.
*'''Recover''': Will fail if the user has either 511 below max HP or 255 below max HP.
*'''Rest''': Will fail if the user has either 511 below max HP or 255 below max HP.
*'''Reflect''': Its effect will disappear if the user is switched out, but if you do not, the effect will remain active until the user faints.
*'''Roar''': Has no effect.
*'''Selfdestruct''': Its base power is 130 (260 after defense is halved). If is used against a Substitute and breaks it, the user will not faint.
*'''Softboiled''': Will fail if the user has either 511 below max HP or 255 below max HP.
*'''Substitute''': A Substitute does not block status inducing moves other than poison, confusion, the effect of partial trapping moves, or secondary effect confusion. It also blocks the effects of stat reducing moves and Leech Seed.
*'''Thunder''': Has a 10% chance of paralyzing the opponent (not 30%).
*'''Whirlwind''': Has no effect.
*'''Wrap''': See Partial-trapping moves.




== Stat and damage formulas ==


===== Stat formula =====

The final Stats (HP, Attack, Defense, Special and Speed) can be determined using these formulas:

'''Final Stat = 5 + { Level / 100 x [ (Base Stat x 2) + 2 x IV + EV / 1024 ] }'''

'''Final HP = 10 + { Level / 100 x [ (Base Stat x 2) + 2 x IV + EV / 1024 ] } + Level'''

*'''Level''': The Pokémon's current level.

*'''Base Stat''': A fixed value from 5 to 255 that each Pokémon has for each stat.

*'''IV (Individual Value)''': A random assigned variable that can take values from 0 to 15. The HP IV, however, depends on the other Stat IVs. If the Attack, Defense, Special and / or Speed IV is odd, the HP IV will have 8, 4, 2 and / or 1 extra point(s) respectively. Maximum value is still 15.

*'''EV (Effort Value)''': A random assigned variable that can take values from 0 to 65535. The result of dividing the EV / 1024 is rounded down.

*'''{ }''': The result is always rounded down.

Since when battling competitively all Pokémon are usually at level 100 and have the maximum EV (65535) and IV (30), the Stat formula can be reduced to:

'''Final Stat = Base Stat x 2 + 98'''

'''Final HP = Base Stat x 2 + 203'''


===== Damage formula =====

The formula used to calculate the damage inflicted is:

'''Total damage = {([(Level * CH * 0.4) + 2] * Attack * Power / 50 / Defense) + 2} * X * Random / 255'''

*'''Level''': The Pokémon's current level.

*'''CH''': 2 if the attacker scores a Critical Hit. 1 otherwise.

*'''Attack''': The Attack (if used a physical move) or Special Attack (if used a special move) Stat of the attacker.

*'''Power''': The Base Power of the move used.

*'''Defense''': The Defense (if used a physical move) or Special Defense (if used a special move) Stat of the defender.

*'''X''': Includes 1.5 for an attack matching your Pokémon's type (STAB), 2 for each weakness, 0.5 for each resistance, 0 for immunities. All values must be multiplied together.

*'''Random''': A random value from 217 to 255.

*'''[ ]''': At level 100, this expression is 42.

*The result is always rounded down.


===== CRITICAL HIT FORMULA =====

The chances of scoring a Critical Hit are:

'''%CH = Speed * X * 25500 / 131072'''

*'''Speed''': The Base Speed of the attacker.

*'''X''': 8 if the move used has a high Critical Hit ratio; 1 otherwise. If the final %CH result is 255/256 or higher than 255/256, the %CH result becomes 255/256.


===== Stat modifiers =====

Some moves can boost or reduce one stat by 1 or 2 stages. Some status afflictions also affect a Stat, reducing it by a maximum of 6 stages. Also, note that a Stat cannot go over 999. The Stats are affected in this way:


'''Attack, Defense, Speed, and Special'''

-6 = 25%

-5 = ~29% (2/7)

-4 = 33.3%

-3 = 40%

-2 = 50%

-1 = 67.7%

+0 = 100%

+1 = 150%

+2 = 200%

+3 = 250%

+4 = 300%

+5 = 350%

+6 = 400%


'''Accuracy'''

+0 = 100%

-1 = 75%

-2 = 60%

-3 = 50%

-4 = ~43% (3/7)

-5 = 37'5% (3/8)

-6 = 33%


'''Evasion'''

+6 = 33%

+5 = 37'5% (3/8)

+4 = ~43% (3/7)

+3 = 50%

+2 = 60%

+1 = 75%

+0 = 100%

[Andeby]

Here`s some pretty competitive relevant move oddities in GSC:

Changes from ADV to GSC

• Rest won`t fail when chosen by Sleep-Talk, if the Pokémon has less than full health. The user will "fall back to sleep", and the sleep-counter will reset.
• A phazing move (Roar/Whirlwind) will, on the contrary, fail when chosen by Sleep-Talk
• When two Pokémon use a phazing move at the same turn, the fastest user will fail.
• Only one layer of Spikes can be placed on the opponent`s field at any given time.

Feel free to reword if needed.

[Crystal_]

Roar/WW won't necessarily fail when chosen by Sleep Talk, but when the user goes before the opponent. This rarely happens when the move is used under normal conditions as Roar/WW have negative priority, but behind sleep talk, you'll see misses much more often since it'll just depend on whether you are slower or faster than your opponent.

[Jellicent*]

Implemented all of those, thanks guys (especially Crystal_. Damn was that useful! ^.^)

[Zowayix]

I'm pretty sure that sleep lasts 0 to 6 turns in RBY.

This website:
http://www.dragonflycave.com/status.aspx
says that sleep is 1-7 turns in both RBY and GSC, except that in RBY, the counter is decremented before it is checked, which makes it 0-6 in RBY.

[Andeby]

Originally Posted by Fat Crystal_

Roar/WW won't necessarily fail when chosen by Sleep Talk, but when the user goes before the opponent. This rarely happens when the move is used under normal conditions as Roar/WW have negative priority, but behind sleep talk, you'll see misses much more often since it'll just depend on whether you are slower or faster than your opponent.

You are obviously correct. My apologies

[Danilo]

taunt last for two turns in adv

[Borat]

This was weird to follow.

[Jorgen]

Originally Posted by Fat Zowayix

I'm pretty sure that sleep lasts 0 to 6 turns in RBY.

This website:
http://www.dragonflycave.com/status.aspx
says that sleep is 1-7 turns in both RBY and GSC, except that in RBY, the counter is decremented before it is checked, which makes it 0-6 in RBY.

Yes, this is true. However, since you're incapacitated when waking up from sleep, you might as well think of it as 1-7 turns.

[Jellicent*]

Corrected the sleep in RBY thing. Also, added in Taunt for ADV (and DPP), as well as changes to Encore.

Originally Posted by Fat Borat

This was weird to follow.

Right now, I'm just hammering out the actual mechanical changes. The final letter should reflect these differences just as well to an RBY player as they would to a BW player. This is just a rough draft to find any missing major changes~

[meteor64]

Something should be mentioned about Counter/Mirror Coat treating Hidden Power as Physical regardless of its type in ADV (not sure about GSC)

[Borat]

Originally Posted by Fat Jellicent

Corrected the sleep in RBY thing. Also, added in Taunt for ADV (and DPP), as well as changes to Encore.


Right now, I'm just hammering out the actual mechanical changes. The final letter should reflect these differences just as well to an RBY player as they would to a BW player. This is just a rough draft to find any missing major changes~

I guess it's just from an order view. I would've expected RBY -> GSC changes, GSC -> ADV changes, etc. Kind of like an evolution of the Pokemon game. Rather than going back in time, so to speak.

[Golden Gyarados]

Originally Posted by Fat Borat

I guess it's just from an order view. I would've expected RBY -> GSC changes, GSC -> ADV changes, etc. Kind of like an evolution of the Pokemon game. Rather than going back in time, so to speak.

I see where Jellicent is coming from with the order - the majority of players are latest gen players, and if they're going to test the waters of old gens, they'll probably start at the latest and work backwards from there. From that perspective, learning what mechanics differ going back in time is the best way to present the info.

As a Gen I and II player only, I also had a hard time following at first, but I'm not the target audience for this letter, so I dig it :)

[Jorgen]

Originally Posted by Fat meteor64

Something should be mentioned about Counter/Mirror Coat treating Hidden Power as Physical regardless of its type in ADV (not sure about GSC)

Does the same in GSC.

[meteor64]

Fair enough. Also for DPP to ADV, in ADV when the faster mon faints (either from boom or switching in and taking spikes) the opposing mon doesnt get to move, which can be a pretty crucial mechanic to abuse.

[shrapn3l]

maybe mention that night shade and seismic toss hit everything in rby. clears up the thing about counter not hitting ghosts even in the instance of countering seismic toss and it's a notable difference anyway.

also about roar going second in gsc maybe just mention that phazing moves, counter, and vital throw must go second in order to succeed and the slower mon goes second in an instance when two negative priority moves are used at once. something like that.

[Jellicent*]

Big thanks to all you guys ^.^

Mmk, everything's been updated. If there's anything else missing, let me know. Otherwise, I'll be writing it up fully, moving it to Letters, and getting GP on this in the coming days. If you find anything vital missing after it's up, I can always edit it on the SCMS~

[Mr.E]

You might want to point out that the HP DV (we didn't call 'em IVs in my day) pre-ADV is based on the other four stats, rather than having its own individual value. It's not competitively relevant in RBY, since Hidden Power didn't exist yet to justify non-max stats, but it's a good reason you'll never see anyone use HP Grass Electrics in GSC. (i.e. Quagsire will setup on them.) Gender in GSC is also based on the Attack DV, with females occupying the lowest values based on the gender ratio of the species, so you know every physical attacker that isn't a genderless or always-female species will be male.

Counter in RBY only works against Normal and Fighting attacks rather than all physical attacks.

[meteor64]

Gah, I keep missing out important things- in Adv sandstorm doesn't boost the sp.def of rock types, and additionally a freshly sent out pokemon can gain lefties recovery.

I keep thinking of tidbits here and there so I'll just keep this updated.