I'll start.
Krabby & Kingler were always my favourite mons. Was excited when Ash caught a Krabby early on in the anime series, but then it was neglected the rest of the season and I lost hope it would ever get its chance to shine. Cut to me watching the episode where Ash finally has his first league battle and, to my surprise, he picks Krabby! Against all odds, Krabby defeats his first oponent, evolves in the process and then proceeds to sweep the rest of the rivals' mons! I was ecstatic. Kingler has been neglected pretty much the rest of the series and it's always been a shitmon (games, TCG, you call it), but I've always appreciated that Krabby and Kingler got that one episode to themselves.