>>27778188>>27778328Smogon also does tours! Which means if there's a top tier strategy, even if it's only something a few top tier players can utilize, it sees tour usage.
Tangrowth was extremely common in tours. It took a long time for ladder to catch on, which results in
>>27778492Cresselia, on the other hand, gets zero tour usage. Pure Psychic is an awful typing and it's horridly slow. It's enormous defenses still aren't high enough to not get 2 shot by the hardest hitting threats in the game. Against weaker mons Cressy tanks pretty well but against those mons you don't need a wall dedicated to them.
Resistances and abilities >>> raw stats for defensive mons. Cress has none of the former, leaving it outclassed despite the fact it has tons of the latter. The reason it's so good in doubles formats is because so many moves have their power reduced by splitting, it's EQ immune, set up sweepers don't exist, it can be paired with intimidate users to more easily bolster is defenses, raw stats are better defensively in doubles than singles because there's less time to switch making resistances less useful, and it has insane speed control because of Icy Wind, Trick Room, and Thunder Wave. Singles and Doubles are significantly different metagames, and Cressy is UU because of that.