"Sorry, no fire Pokemon. But I do have the next best thing." said All Might, the skeleton-like man pulling out a Geodude.

Knocking a hand against the wall, he added, "There's flint in the cave structure. If we can knock it off and then use it to start a fire with friction, we should be able to get warm."

Because this world was silly like that, having random flint deposits.

"How are you holding up? Do you need my jacket as well?"