Note: This topic is not about whether or not we need a species clause. I know it's a large assumption, but in this topic I'm assuming we want a species clause.
Species Clause was implemented in order to prevent multiples of extremely powerful pokemon from appearing on the same team. Back in RBY, the simplest way to do that was to just ban multiples of the same species from appearing on the same team. That worked fine then, but banning by species number is no longer acceptable. Some nearly identical pokemon of different species can use identical sets for nearly identical effectiveness but are allowed on the same team. Other pokemon with different base stat spreads, typing, abilities, or movepools are not allowed on the same team because they share the same species number.
Both of these problems are handled by using, "No two pokemon that can function in the same way with nearly equal or equal competitively practical effectiveness may be permitted on the same team," as a guideline for the bans. When it comes to making the bans, we can use "same sprites" as the primary means of banning (since usually only pokemon of the same sprites satisfy these conditions) and then explain any additional bans or allowances afterward. There's relatively few, so this method looks perfectly acceptable.
I may be getting ahead of things and expanding the scope of this post too much, but I'll post my evaluations of particular "exceptions and allowances" now. They were already done anyway, so even if we scrap this idea, there's no harm done. The standard I will be applying and I advise you to apply for "nearly equal effectiveness" is extremely stringent. Too loose may result in unnecessary bans. If you decide to use a more loose standard, just explain your rationale.
The following pokemon are from different species and can run the same set equally or nearly equally well.
Clefable line
"Lv.2 Endeavor", from the analysis:
Lv.1/Lv.2 Clef @ Focus Sash
Ability: Magic Guard
- Endeavor
- Protect
- Encore
- Thunder Wave / Sing / Toxic
The unique circumstances surrounding these pokemon and this set render them functionally identical. I see no reason to allow any of them on the same team.
The remaining sets of pokemon are similar pokemon that have traditionally been banned from appearing at once. By default, they should all be allowed at once unless we can find a set the forms run nearly equally well.
Deoxys
I don't see any argument that can be made to ban any of these from appearing on the same team except for Deoxys-N and Deoxys-A. The difference in offenses is big, but big enough to treat them separately? The best set to test is probably the +speed LO 4 Atk / 252 SpA set. Here are some damage calculations:
Deoxys-N
Superpower vs. neutral 0/252 Blissey : 97.39%-114.59%
vs. neutral 252/0 Dialga: 67.82%-80.20%
Ice Beam vs. neutral 252/60 Groudon: 75.74%-89.11%
vs. neutral 248/12 Giratina-a: 50.50%-59.64%
vs. neutral 252/0 Lugia: 49.52%-58.65%
Thunder vs. neutral 252/0 Lugia: 62.50%-73.56%
vs. neutral 4/0 Kyogre: 82.46%-97.66%
vs. neutral 0/0 Palkia: 50.47%-59.50%
vs neutral 176/176 Scizor: 57.23%-67.38%
vs. positive 252/252 Forretress: 52.54%-61.86%
Shadow Ball vs. neutral 4/0 Mewtwo: 77.97%-92.07%
vs. positive 28/252 Wobbuffet: 47.73%-56.44%
HP Fire (rain)* vs. neutral 176/176 Scizor: 67.69%-80.00%
vs. positive 252/252 Forretress: 62.15%-73.45%
Deoxys-A
Superpower vs. neutral 0/252 Blissey: 114.59%-134.87%
vs. neutral 252/0 Dialga: 79.21%-93.56%
Ice Beam vs. neutral 252/60 Groudon: 87.13%-102.97%
vs. neutral 248/12 Giratina-a: 58.05%-68.39%
vs. neutral 252/0 Lugia: 57.21%-67.31%
Thunder vs. neutral 252/0 Lugia: 71.36%-84.62%
vs. neutral 4/0 Kyogre: 95.32%-112.28%
vs. neutral 0/0 Palkia: 57.94%-68.22%
vs. neutral 176/176 Scizor: 65.85%-77.54%
vs. positive 252/252 Forretress: 60.45%-71.19%
Shadow Ball vs. neutral 4/0 Mewtwo: 89.27%-105.65%
vs. positive 28/252 Wobbuffet: 54.92%-64.77%
HP Fire (rain)* vs. neutral 176/176 Scizor: 77.54%-92.31%
vs. positive 252/252 Forretress: 71.19%-84.75%
*-In both cases, a positive nature for deoxys may be better here since you already lose against most other opposing deoxys. They're not used in these calculations.
Almost all the #HKOs are the same in the majority of cases. Whether this is close enough or not depends on how strict your interpretation for "nearly equal" is. To me, this is adequately close.
Shaymin
Different base stat spreads, different abilities, and different typing - here, they have a significant impact on the differences in play between them. I can't think of a single viable set that these two run nearly equal well. Subseed seems closest, but not close enough.
Giratina
Different base stat spreads, different abilities, one is locked into an item which the other cannot use. I'm hardpressed to think of a set these two could conceivably run nearly equally well. CM/Dragon Pulse/Restalk is the first thing that comes to mind, but the difference in bulk and items makes that seem unlikely. If you have any ideas, by all means.
Wormadam
Different base stat spreads, different typing. At first glance, they look very different, but I have no experience with Wormadam.
Rotom
This has already been discussed in another topic.
http://www.smogon.com/forums/showthread.php?t=46787
The final decision was arrived at in the same manner as if it would have been done here. What Calciphoce said here
http://www.smogon.com/forums/showpost.php?p=1533910&postcount=19
I've also thought about, but no one else said anything then, so apparently most people didn't find it significant.
Species Clause was implemented in order to prevent multiples of extremely powerful pokemon from appearing on the same team. Back in RBY, the simplest way to do that was to just ban multiples of the same species from appearing on the same team. That worked fine then, but banning by species number is no longer acceptable. Some nearly identical pokemon of different species can use identical sets for nearly identical effectiveness but are allowed on the same team. Other pokemon with different base stat spreads, typing, abilities, or movepools are not allowed on the same team because they share the same species number.
Both of these problems are handled by using, "No two pokemon that can function in the same way with nearly equal or equal competitively practical effectiveness may be permitted on the same team," as a guideline for the bans. When it comes to making the bans, we can use "same sprites" as the primary means of banning (since usually only pokemon of the same sprites satisfy these conditions) and then explain any additional bans or allowances afterward. There's relatively few, so this method looks perfectly acceptable.
I may be getting ahead of things and expanding the scope of this post too much, but I'll post my evaluations of particular "exceptions and allowances" now. They were already done anyway, so even if we scrap this idea, there's no harm done. The standard I will be applying and I advise you to apply for "nearly equal effectiveness" is extremely stringent. Too loose may result in unnecessary bans. If you decide to use a more loose standard, just explain your rationale.
The following pokemon are from different species and can run the same set equally or nearly equally well.
Clefable line
"Lv.2 Endeavor", from the analysis:
Lv.1/Lv.2 Clef @ Focus Sash
Ability: Magic Guard
- Endeavor
- Protect
- Encore
- Thunder Wave / Sing / Toxic
The unique circumstances surrounding these pokemon and this set render them functionally identical. I see no reason to allow any of them on the same team.
The remaining sets of pokemon are similar pokemon that have traditionally been banned from appearing at once. By default, they should all be allowed at once unless we can find a set the forms run nearly equally well.
Deoxys
I don't see any argument that can be made to ban any of these from appearing on the same team except for Deoxys-N and Deoxys-A. The difference in offenses is big, but big enough to treat them separately? The best set to test is probably the +speed LO 4 Atk / 252 SpA set. Here are some damage calculations:
Deoxys-N
Superpower vs. neutral 0/252 Blissey : 97.39%-114.59%
vs. neutral 252/0 Dialga: 67.82%-80.20%
Ice Beam vs. neutral 252/60 Groudon: 75.74%-89.11%
vs. neutral 248/12 Giratina-a: 50.50%-59.64%
vs. neutral 252/0 Lugia: 49.52%-58.65%
Thunder vs. neutral 252/0 Lugia: 62.50%-73.56%
vs. neutral 4/0 Kyogre: 82.46%-97.66%
vs. neutral 0/0 Palkia: 50.47%-59.50%
vs neutral 176/176 Scizor: 57.23%-67.38%
vs. positive 252/252 Forretress: 52.54%-61.86%
Shadow Ball vs. neutral 4/0 Mewtwo: 77.97%-92.07%
vs. positive 28/252 Wobbuffet: 47.73%-56.44%
HP Fire (rain)* vs. neutral 176/176 Scizor: 67.69%-80.00%
vs. positive 252/252 Forretress: 62.15%-73.45%
Deoxys-A
Superpower vs. neutral 0/252 Blissey: 114.59%-134.87%
vs. neutral 252/0 Dialga: 79.21%-93.56%
Ice Beam vs. neutral 252/60 Groudon: 87.13%-102.97%
vs. neutral 248/12 Giratina-a: 58.05%-68.39%
vs. neutral 252/0 Lugia: 57.21%-67.31%
Thunder vs. neutral 252/0 Lugia: 71.36%-84.62%
vs. neutral 4/0 Kyogre: 95.32%-112.28%
vs. neutral 0/0 Palkia: 57.94%-68.22%
vs. neutral 176/176 Scizor: 65.85%-77.54%
vs. positive 252/252 Forretress: 60.45%-71.19%
Shadow Ball vs. neutral 4/0 Mewtwo: 89.27%-105.65%
vs. positive 28/252 Wobbuffet: 54.92%-64.77%
HP Fire (rain)* vs. neutral 176/176 Scizor: 77.54%-92.31%
vs. positive 252/252 Forretress: 71.19%-84.75%
*-In both cases, a positive nature for deoxys may be better here since you already lose against most other opposing deoxys. They're not used in these calculations.
Almost all the #HKOs are the same in the majority of cases. Whether this is close enough or not depends on how strict your interpretation for "nearly equal" is. To me, this is adequately close.
Shaymin
Different base stat spreads, different abilities, and different typing - here, they have a significant impact on the differences in play between them. I can't think of a single viable set that these two run nearly equal well. Subseed seems closest, but not close enough.
Giratina
Different base stat spreads, different abilities, one is locked into an item which the other cannot use. I'm hardpressed to think of a set these two could conceivably run nearly equally well. CM/Dragon Pulse/Restalk is the first thing that comes to mind, but the difference in bulk and items makes that seem unlikely. If you have any ideas, by all means.
Wormadam
Different base stat spreads, different typing. At first glance, they look very different, but I have no experience with Wormadam.
Rotom
This has already been discussed in another topic.
http://www.smogon.com/forums/showthread.php?t=46787
The final decision was arrived at in the same manner as if it would have been done here. What Calciphoce said here
http://www.smogon.com/forums/showpost.php?p=1533910&postcount=19
I've also thought about, but no one else said anything then, so apparently most people didn't find it significant.