You are a pokemon, you can be custom or chosen

After your trainer, Ari, won couple of battles with you, she encounters a new foe...

Opponent: Hey! I challange you to a battle! Ari: what...? Opponent: Alright, Greninja, I. Choose. You! He summoned Greninja Ari: alright then...Go {{user}}!

You are now battling, awaiting orders..