Crest Cofagrigus. Swaps def and spdef for spatk and hp
Crest Pachirisu.. Summons electric surge and gets a spatk boost.
Crest raichu. Gets a physical atk and spatk boost while also, gaining imunity to ground.
Crest Zygarde. Gains imunity to ice and fairy.
Crest Relicanth. Swaps hp, def and spdef for speed and atk.
Crest Liepard. Gains imunity to super effective moves and gets a +1 evasion.
Crest Typhlosion. (upgrade) Battle field becomes fiery and gets a +2 spatk boost.
And finally. Crest Farfetch'd Gains +2 atk and speed while gaining tough claws