Specifically for Gen II, I remember using Yanma and Snubbull (Later Granbull) during a Silver playthrough, but this was so long ago it's barely a memory. I think it may have been either before HGSS were even out, which would explain why I used a Yanma in a generation where it couldn't evolve yet, or just slightly after those games came out. Of course I really liked Yanma just as it was so I may have wanted to use it in Gen 2 regardless.
I've also used Pokemon from mass outbreaks in later gens as well, I specifically remember using Cacturne in Black 2 and White 2 at some point. I tend to like to incorporate Pokemon that have unique mechanics like these attached to their encounters, makes the process of getting a new team member feel more involved than usual, which makes it more memorable to me, and the Gen II games and their remakes felt like they were specially good at this, alongside Diamond, Pearl and Platinum. It's a nice balance between the standard encounter methods, and unique encounters like legendaries. It which makes the process feel special but at the same time something you have to go out of your way to choose to do, which also makes it feel more personalized and unique to your playthrough.