Alright, here's some crests for some unnoticed mons.(well at least one of them.)
Vileplime: Merges both its Def & SpDef, and allows it to hit and poison steel types with poison moves.
Bonus: Only when it first switches in, it will gain passive recovery (basically a free leftovers or black sludge).
Bellossom: Merges both its Atc & Sta, and makes it immune to fire attacks (essentially Flash Fire).
Bonus: Only when it first switches in, this mon will summon harsh sunlight for 8 turns.