Mewtwo? Just that... he seems to think humans are using Pokemon as slaves. And the ones who want to be with humans, they're just weak. He can't seem to understand that it's possible to be friends with them - that they want to help their trainers.

[Although, having said that, Lucas doesn't know much about the battling side of things. If he did, he'd likely start to see where Mewtwo was coming from.]

I've met a boy named Trip and his Pokemon seemed happy enough. Yours do too!