I think the critical factor here, is we are dealing with multiple pokemon, Politoed with some pokemon setup, makes some pokemon broken. Politoed + Weather Abuser, isn't one pokemon, and you can't ban a pokemon for something alone it can't do, and Politoed itself isn't broken, you you can't ban it either. But, you can ban certain combinations, which are broken, similar to clauses, its like I said in the past, you can't compare the species clause with Mewtwo, they are 2 totally diferent subjects.
Now I can see the arguement of "Well X pokemon might be broken with Y support, so you could say that we could ban the combination of those 2 pokemon on a team." While this is certainly valid, I should note again, the scale of Politoed's influence, alone it can break 4 pokemon, and many more can be debated. So its a much bigger force then just X+Y pokemon, but more of like X+(Y1, Y2, Y3, ect). Which if you look at it, goes more along the line of a clause, not a ban, becuase of its such vast diference.
Now a clause, such as the moxie clause, has a wide impact over the whole metagame, without it every pokemon with moxie is broken. But the combination clause is a very diferent case, it only bans some pokemon broken combinations. And its not universal either, or else such a clause would be in effect in the Uber metagame, and it clearly isn't. Why? Becuase its not broken there, and thats the key point, it already has proven to be universally not broken, but only breaking many pokemon in the right standard, situation.
I would like to compare the Wobbuffet ban in 4th gen, to the combination ban, which I believe are 2 very similar situations. Wobuffet, with shadow tag and encore has the capability to break many pokemon with the support it gave, similar to Politoed. Now theoritically in 4th gen, we could of created a Wobbuffet complexity clause, which would have banned wobbuffet in combination with several pokemon which with it would have banned several pokemon/moves (swords dance or dragon dance) in combination with it. And of course we would have not have banned such combos in Uber, and if I had my way, would not have banned every pokemon with a boosting move/certain boosting pokemon in combination with it. But instead of all this mess, we decided to just ban Wobuffet. Whats the diference between them? A few big diferences actually, most of which deal with move tiering which I disagree with as opposed to ability tiering with Politoed, although that diference is debatable.
But the biggest diference is using Wobbuffet on a team, is not a playstyle, its a pokemon, one single pokemon. Using wob on a team isn't a team, but Politoed on a team is, we don't write articles on how to make a team with Garchomp, but we to write them about making a hail or sand one, why? They are big independant, parts of the metagame, which should be saved at all costs, while a single pokemon can be swept under the rug.
