I think I understand everything a bit better now.
Okay, so there are humans and there are Pokemon.
And sometimes the humans goof around, and sometimes it's the Pokemon.
Sometimes the Pokemon ARE humans, changed, like Ashachu, by a Pokemon magician (or a magic potion)
Fortunately for the rest of us, it's only temporary. o_~
I'm not sure who these two guys are, but I suspect Doryuzu-kun is the mischievous one.