They were both antagonists at some point.

They're in the Galar Pokedex

It feels weird that a ball shooting smoke and a 2000 lbs dragon are the same type

They can both learn Toxic

@BottedAccount Yeah, i realized they were poison-types right after I made this post lol

They both look like they're smiling ^U^

Both from the Galar Dex

One has a skull and crossbones design on it and the other is basically just a skeleton

Theyre both toxic

Both poison types and they fly