Normals:
Pretty much every team will benefit from using

, even Wrap teams. I don't think stall is a good options. Even if your team doesn't have room for

in the back, it is still can be run as a very useful lead. As a lead it can score crits and immediately put you at an advantage, it can also coerce players into clicking Thunder Wave. But you should make sure that your team doesn't need it as a sweeper/revenge killer. It has to choose between Hyper Beam and one of its other moves a lot, which puts you in 50/50 situations a lot. Its moveset is almost always the same, but it doesn't need to do any surprising to be good.
Many Pokémon depend on

to be able to have something to switch into. If Chansey dies, you will need to depend on the Psychics for taking hits. Chansey's Normal typing makes it harder to paralyze and to take be taken down by Special moves. Chansey helps enable wall breaking with its access to Thunder Wave. It can take on the likes of Rhydon and Starmie with its Bolt Beam coverage. It can also play the role of a sleeper with Sing. Because it needs to be able to wall special attackers, it won't be a dependable answer to Snorlax and Tauros throughout the entire match. As far as I know anyways. But early game, I can see it walling out lax.

is a powerful physical attacker that can choose to be mixed. It can be used to wall out opposing Snorlax and Tauros. It's hard to take down, hard to know what it's going to do, and it can help break through teams.
I think that because

and

can run so many sets, it makes them more unpredictable, which adds to their strength. Though if you look at the opponent's team comp, you can reason out what it might have, if the team is frail to

, the opposing

will very likely be running Reflect. And teams will generally want to run Reflect. The final move could probably be anything honestly... Even if the opponent's team is weak to Rhydon, it could end up being mono Normal b/c reasons/to surprise people. Though my guess is that the likelyhood of sets that show up will be in this order: Reflect+Selfdestruct, Reflect+Hyper Beam, Reflect+Ice Beam, Reflect+Earthquake, Amnesia Mixed with Blizzard/Ice Beam, All out Attacker, Bolt Beam, Mono Ice, Mono Electric, Reflect + Amnesia Mixed, Random Coverage, Mixed Normal + Thunderbolt, Reflect + Counter, Reflect + Amnesia Normal, Reflect + Toxic, Reflect + Level 85 Seismic Toss. Reflect + Earthquake is only for catching Gengar off guard/staving it off, and having a fighting chance against Rhydon. I'm not sure how useful Earthquake is when you are running two other Psychic types.
Their flexibility may be able to help them to adapt to whatever gets popular.
These are the reasons why you may find one replaceable:

1. Need more offense

1. It's going get walled out anyway, and I have other mons to wall out

. I need another Special wall.
2. My offensive team doesn't have room for it, it will get walled out anyway, and my team does not have enough paralysis support to make use of it. (more for fun teams)
A Chanseyless team may look like this:






or this:






A Snorlaxless team may look like this:





Given how good the Psychic Types are, I can see why

is considered more replaceable than

.
Psychics

is probably the best psychic in my opinion. It sleeps something, it can Paralyze something, it provides a switch in to Rhydon and predicted Earthquakes from Snorlax, and it can Explode to remove an important threat. Rest is a fun option which can make players think it doesn't want to Explode, and it can also help keep it around. Leech Seed is generally a wasted moveslot.

is an annoying mon that won't go down, except against Thunderbolt, and Razor Leaf, if it shows up. Bolt Beam weakens it against

, but provides good coverage. It's probably a bad idea to run bolt beam. Running Surf means it's more likely not going to run Blizzard which means it will get walled out by

. Though, this may not matter unless you need to prevent it from blowing up. If it doesn't run Thunderbolt, it gets walled out by

. It also gets walled out by

. The best combination, in my opinion, is Thunderbolt + Psychic due to Psychic's special drops, and due to being able to take on Slowbro without depending on Explosion, and to take on opposing

. It could run three attacks on occasion if it means winning the game, though it loses either the move that makes it not die or the move that supports your team. It can be a good idea to pretend that your

is struggling against a mon to make the opponent think has the wrong coverage move.

hits hard when it crits and is also arguably the best lead. Although, when

switches in, it doesn't know if

wants to click Sing or Thunderbolt. It also might not want to be sleep fodder because it can at least do something against

. Usually, it wants to switch into

when it is weakened enough.

A good special wall that is annoying to take down, but it doesn't like to be hit on the Physical side. It notably walls a number of

sets and pesters it and forces it to switch due to stat drops. (I am unsure how well Zam does against Seismic Toss). It hits hard with Psychic. It can wall

though

is better at that.
B Tier

is a monster that makes you have to think twice about how you build your team. It hits very hard on the physical side and is generally very hard to switch into. It can sponge Explosions for your team. It can also wall out Normal

. It is unfortunately slow and gets hit hard from the special side, making it hard to switch in.

while inaccurate, its ability to add an additional Explosion is very useful. It can wall out

, and is pretty likely going to be able to, or at the very least it can act as a pivot if Snorlax has Earthquake (though it's not perfectly safe to use it that way). It works well with

, because if the opponent uses their Sleeping mon as fodder for Explosion, then you just shrink their team again with Hypnosis/Sleep Powder.

is a nice switch into

and

. Clamp and Explosion are both very useful tools that other

walls lack. These two moves are what make it able to stop

from healing, straight up KO it, or just to provide safe switches. Explosion allows it to remove a threat. It is not going to take Body Slams as well as the Rock types and paralysis, burn, and poison remove the effectiveness of Clamp. Body Slam will be likely to eventually paralyze it forcing it to Rest. Clamp missing can be very detrimental and Clamp draws in sleeping Pokemon, who may try to use Clamp's minimal damage to wake up, or to coerce you into switching out.

a lead, an additional sleep user, or just your sole sleep inducer in the back. It has nice STAB moves. Frail on the physical side but can use Counter to dissuade physical attacks.

is a very strong mon that can take on important threats such as:

,

,

,

,

,

, But it has a very rough time against Rock/Ground types, and letting

in so easily is very unfortunate. It also likely doesn't like running into any of the Ground types such as

. It is also walled by

and arguably trades with

. When it isn't being walled, it will likely take something down.
C Tier

is a very scary mon. It forces Explosions, or you to have a Thunderbolt or Razor Leaf as an answer. And you have to depend on Thunderbolt actually critting. Its paralysis support is useful too. One weakness may be its dependance on Rest.

Slash is nice for taking on Snorlax and

. it has access to both Bubblebeam and Thunderbolt, which makes it harder to be walled by

and

. Growl and Screech are options to scout for Counter. Its Normal typing means it won't get paralyzed by Body Slam, though it won't be taking too many of those. It is also walled by

The only reason why I think it may be better than Articuno is its access to Thunderbolt, making it harder to wall outside of just Chansey. It's a decently bulky mon. Confuse Ray is annoying.

There are plenty of Pokemon that will wall

:






. Which holds it back, a lot. It can scare out

as well as hit

and

hard. It removes

which will be a there to faint in the end game. It has the potential to sweep.

A very similar mon to

. Though, it is more of a high risk high reward sort of mon. It's Fire Spin enables it to weaken foes, turning a 2 HKO on

to a 1HKO and a 3 HKO on

to a 2HKO. Fire Spin can also make up for Burning Starmie as well as allow it to pivot. It also has a better matchup to

and

than

does. One key difference is that

can switch into

and threaten a KO. Though

won't be taking Fire Blasts forever.

is sort of a worse

. It is faster and can crit a lot, but its coverage moves are pretty bad.

probably prefers Rest over Pin Missile due to allowing it more chances to Double Kick

more and to out speed mons during the end game. Pin Missile is inaccurate, and depends on chance to be able to take on

. Pin Missile is also an easy move to switch into. It gets hard walled by Ground types and is more fragile to Psychic type moves than the Psychic types. Its main uses are to take on

,

, and

, and maybe sweep or weaken the physical Normals.

I don't agree with

being stronger than

. Kabutop's typing allows it to beat Amnesia Normal/Ice

, Ice Beam + Reflect

, and Normal

, and some important paralyzed mons. Against Reflect Lax, it can Rest loop it as it sets up Swords Dance. A big weakness that I initially did not notice, is that it is unsafe for

to initially switch into

with no fear, since

could always be running Earthquake. I usually have

to scout for Ice Type moves, because I believe that the two work decently well together. There are ways to scout for it, but it's something to pay attention to. One thing :Perisan: has over

is its ability to take on

. The other being that its speed allows it to hit Tauros before it dies.

is vulnerable to Body Slam paralysis and can always die to a crit Earthquake. That being said,

's resistance to Normal does allow it to Sponge Explosions and come in on predicted Hyper Beams, the latter potentially allowing it to setup.
Outside of the whole scenario where you run

or

with Zapdos to lure in Rhydon, I think Kabutops is overall better. If

sets up sets up a Substitute in front of

as you switch-in

,

will lose most of its HP, unless you happen to have a good switch, which you probably won't given that two slots are being used up. My guess is that players are expecting to use

against a

that was weakened by another Reflect

in order to set up Swords Dance as Snorlax Rests, or switches out in a weakened state. Which is an option...

is so low because of how fragile it is. Though its access to Wrap helps it to spread damage, and it helps it to put something to Sleep even if another Pokemon is paralyzed, lest that mon wants to get Wrapped and KOed. It does a good job at spreading status, getting in a safe switch, and spreading damage. If Wrap or Sleep Powder misses, it's probably going to die.

same reason as

, though

is more fragile, and doesn't have Sleep Powder. But its Agility Wrap set can be terrifying in the end game.
D Tier

is here because it serves a purpose of walling out

. What I think it has over

is the ability to deal damage, and do something outside of walling

. Like sitting in front of a weakened

firing off Blizzards or Ice Beams. Or trying to take down

with Hydro Pump. It can also switch into predicted Explosions and Hyper Beams. Its main weakness is Ground

. It doesn't initially care about Earthquake due to the damage output from Hydro Pump, but over time, it will get paralyzed. When it is paralyzed, it will lose to lax, unless lax got paralyzed along the way. It also has issues with Amnesia

setting up, just like

. But it can run Toxic and have

replace one of its lesser used moves to Leech Seed to force out

with the Toxic + Leech Seed glitch. This is probably the only way to use that glitch. The strategy is not necessarily safe, because Leech Seed can always miss, and Toxic can always land on

. Players are probably going to be too dedicated into setting up for them to want to switch out though. Toxic isn't limited to being used against just

and

, it can be used against

since it is a more reliable way to prevent

from Clamping it to death than hoping for a Body Slam paralysis. Toxic can also be used on lesser used Pokémon that do not have Recovery to put them on a timer and force them to switch in a weakened state.

won't want to sit in against

or

and Body Slam would need to be used on a predicted switch from

.

may be a reasonable teammate to help against

and other Special Attackers.

could replace

to help against opposing

,

, and

, either that, or it would replace

. But you would have to expect not to run into

if you did that imo. Ice Beam/Blizzard can be more of a middle ground type of option against

since it will hit

allowing it to be 2HKOd by Hydro Pump, while also fishing for a Freeze on a potential switch to a Special Wall. Amnesia isn't the most common move that you will run into though, so it's up to you if you want to run Body Slam or Toxic. Anyways, the bottom of E tier seems a little Jank to me... Below

even.

walls out the more common

sets. It generally just presses Recover and does nothing else. This does in fact allow it to PP Stall

, but it lets Pokémon switch in extremely easily. This means that there is a lot more pressure put on

.

or

may be the Pokémon you want to use alongside it. Using

makes you weaker to

. If

switches into

, something is likely going to die. If

is bent on removing

it's a 50/50 speed tie situation to see which wins between the two. I would not try to use any methods to try to beat Amnesia aside from Exploding, since

wants to be paired with a powerful Pokémon, because it won't be doing much Damage. You will probably lose to Amnesia

, but those sets are probably not going to show up as often... But they do show up. You will be able to run an All Out Attacking

set with

which aids your team against threats like

,

,

, and

. Though you will probably want those threats to be paralyzed beforehand. Thunder Wave can potentially cripple

in the endgame, and it also helps prevent

from switching in. It can use Thunder Wave to take out All Out Attacking

. It's a toss up if it wins a Freeze war against lax or not.

is a Swords Dance mon that can switch into

. It is not blocked by

and can hit

pretty hard. I have it so high due to its potential defensive use. Sorry, I am not more in depth on this mon, but I think this is a fairly reasonably position for this mon.

it really is a worse

, but the possibility that it can Explode is pretty scary.

It spreads status and is pretty bulky, but it relies on Rest. I don't have much more to say than that.

Walls Mono Normal Snorlax which is (probably) one of the more common sets. It also walls Normal + Ground Lax, which

does not. This is the main niche that makes me think

can be run in OU. Though, obviously at a disadvantage. It can serve several functions: to pick off weakened Pokémon, to sponge Explosions, chip

and potentially Burn/Crit it with Fire Blast, and it has the potential to get KO's or severely weaken Pokémon with Sky Attack. Unlike

, :Aerodactly:'s aim is and should be to KO

through damage, along with PP stalling and Burning. I think needs to do multiple things, because it will be fighting against parahax. So, the ideal moveset, in my opinion, is Sky Attack, Fire Blast, Double Edge, and Rest. Sky Attack has a (1-(1-.2539*.9)^6)=.78915 chance to crit, unparalyzed, at least once in 6 tries, which nearly KOs

. Though, it has a myriad of issues. It will inevitably get Paralyzed, and the speed drops remains, even if it Rests. It lets in

too easily, and Ice/Normal Ice

beats it. It can run

to fend off Normal/Ice Lax, but

is going to be able to set up a Substitute on

thus forcing a near KO on

. Though, Kabutops, does somewhat mitigate the weakness to

.

can attempt to Fire Blast Rhydon once or more times (depending on if

decides to predict a switch), but the burn chance * the chance for a miss is still too low to consistently help. Critting can at least help bring

into KO range for

. Another option to run alongside it, is Rest+Hypnosis

which frees up

's moveset allowing it to run Bolt/Beam.

fulfills a useful role on Wrap teams.

is a wall breaker that is hard to predict. It's weakness to electric type moves really hurt it. It has a higher crit rate than

and its Body Slams and Hyper Beams are much stronger. You generally want to keep this mon healthy to make use of it.
E Tier
:Khangaskan: an extra Normal Pokemon to throw out Body Slams. Sorry, I dont' have much to say about it, I just want to make sure it's included somewhere.

is a Pokemon that has access to Amnesia and Hypnosis. It can stave off

, though it is extremely vulnerable to crits.

Is a Swords Dance user that has access to Razor Leaf and Sleep Powder. It is unfortunately outclassed by

perhaps this is too low for it... but it is incredibly vulnerable to paralysis, and with Thunderbolt all over the place, I don't see it doing much. It does have a massive Attack stat and nice signature move in Crabhammer, though Crabhammer misses a lot.

is just a Bolt Beam mon that can hit on the Physical side and paralyze something.

While

may seem like a garbage mon, it still plays a role in beating the two Electric types that show up

and

. Bind allows it to act as a pivot as it switches into Rock Slides, Body Slams from

, and Electric type moves from Electric Type Pokémon. Once it's used up, it blows up. I see this as a at least more useful that what

does.

is a

check that staves off

and

. Its damage output is less than desired, which means that it may have a hard time Paralyzing something. Though, KOing itself versus

allows

to be taken on by something else.

is a Swords Dance user that wishes it had access to Earthquake. It can sometimes pivot.

, in order to make full use of

I personally think that you need to be able to manage switching it in on a Sleeping Pokemon then fire off Super Fangs on whatever switches in. Which can only be achieved with a partial trappers, or when the opponent is using a mon a death fodder. The other possibility being that it predicts a switch from a weakened Pokémon. So, I think, its best teammate is

, since it can spread Paralysis and Sleep, and help beat

. Otherwise, I only seeing it firing off Super Fang once, then dying. It requires a lot of prediction/lucky guesses and may be too hard to use.

I don't really believe Fighting Types have much of a chance in the meta. But Machamp has access to Earthquake which helps it against

. Hyper Beam does deal a lot of damage to

and

could be a scary sweeper, though it gets hard walled by

and is rather fragile.

is generally a bad mon in the Tier. It at least has access to Earthquake for when it sets up Swords Dance, but I don't see it doing much other than getting a single hit in. It is the only Flying type with Counter, and players probably ignore

and are more likely not to know what to do against it. Though, that's not saying much considering its typing and damage output.
???
Too much effort for me to figure out where to place them. Runing the pre-evos may have some merit...

is a pivot against

that spreads Status.

would be run alongside

and

b/c of its access to Sleep + Explosion. Access to Thunder Wave and Agility all

to play a role on Wrap teams.