Even though I don't own the thread I think I'll put in my thoughts on this:this is a question out of pure curiousity, but will there be pokemon specific costumes, or is there a costume for each type?
eg: Galvanized Helmet: Changes the secondary type of this pokemon to Electric. Changes the holders ability to Electric terrain. Adds Thunder, Thunderbolt, Wild Charge, Discharge, Thunder Punch and Nuzzle to this pokemon's moveset. Gives + 20 Speed, +10 Attack and Special Attack. loses 10 Defence and Special Defence.
I feel like this could add a new twist to some existing pokemon, and spice up the metagame a bit. just my idea though
-I do like the idea that any Pokémon can hold costumes
-If this does happen, then I think it should work like Z-Moves, it's available to all Pokémon, but certain pokemon get it(That reminds me, I still need to get my Super Pikachu submission in)