It's in his sig.
Also, I feel like lava will probably be the same as all the other times we've seen it in pokemon games - something decorative and and obstacle, but not something to interact with. I can't think of a game other than those of first gen that DIDN'T have lava in some way. Blackthorn Gym, Mt. Chimney, Stark Mountain, White 2's Reversal Mounain...
Lava is pretty much a decorative staple? I have no reason to really believe it's gonna be anything different than what it's been in the past games.
Good catch. Yeah, that's lame of him.
I don't know if I'd want it to be anything other than decorative.