My group (Well one person with the help of another) summoned Mewtwo by channeling the main villain of the story and used him to utterly wreck the enemy character due to our own (minus guy with a strong pokemon) inadequate powers of just coming out of the first gym. He hit the enemy for over 1,000 damage which would of killed him if Mewtwo wasn't friends with the main villain due to them being from a different universe. I also have a uber Dratini with two abilities, a lucky egg, TWO abilities (Marvel Scale, and Moody) and a dangerous moveset. And when he evolves to Dragonite I got a in-universe dragonite-ite a mega evolution for his final form.

And Unown are actually badass. My unown does 2 d20's worth of damage to enemies and it's rock meaning it's uber effective as well.