Sunflora Crest - Sets up sunny day when entering the battle, whilst also making its speed equal to its spatk. (By giving the speed Sunflora desperately deserves, as well as applying sunny day upon entering, it enables Sunflora to actually use its abilities and moves efficiently in battle.)
Kricketune Crest - Gives it +2 atk and +2 speed, whilst also confusing the target upon entering. (Without having the attack and speed to actually be useful in battle Kricketune is unable to pull off many of its moves due to its frail defences, that is also why confusing the target upon entering is useful