Golurk Crest: +1.5 increase in physical attack, defense, special defense. sets up arenite wall even without a sandstorm. +2 priority for shadow punch.
Toxtricity Crest: swaps physical attack and speed. +2 speed. sets up electric terrain upon entry.
Volcarona Crest: gains drought as an additional ability and melts any field hazards.
Noivern Crest: gains aerilate as an additional ability. +2 special attack
Greninja Crest: water shuriken hits 5 times and gets a +1 evasion increase upon entry (so basically a free double team)