It's a giant worm! They're sinking cities with a GIANT WORM.

095: Onix

In an age before Waillord existed, Onix was the original biggest Pokemon. Onix is some sort of rock snake or earthworm, burrowing very deep underground. Onix doesn't cross my mind a lot of the time, but I like the vibe Onix gives off. Onix just looks like it lives for thousands of years, and not a lot of Pokemon have that sort of atmosphere about them, even some Pokemon that are supposed to be thousands of years old. Given a bit more of a gritty stylization, Onix wouldn't look too out of place in something like Shadow of the Colossus. It'd be cool if the look were committed to with moss growing on the thing's boulder segments. It could give a nice splash of color to an otherwise plain Pokemon, as far as colors go. Or at the very least give it heftier earth tones rather than just flat grey all over.