i'd say numel is a pretty big contender looking at it now, like i was talking about pokemon go (more specifically how numel is like the only ground type spawning at the moment), and i realized "fuck dude, when's the last time anyone ever talked about numel?" and here i am now making this thread.
like it's not outright mundane like say, pidgey for instance, but there's not much to really talk about either. the most noteworthy thing i can think of about it is that as a kid there was this one AG dvd that had some eps on it and one of them was about numel.
gen 3 has a lot of kind of forgettable pokemon, actually. when's the last time you thought about breloom? or swalot? it's not like i just don't have experience with gen 3 i've played oras multiple times and imo they're quite possibly some of the best games in the series, there's just a lot of pokemon that are just. oh yeah they sure do exist.
before i just start listing off gen 3 pokemon dubiously honorable mentions to delcatty, tropius, and exploud
on a more positive note, however, a genuinely honorable mention for qwilfish and the comeback it's made in legends arceus! i remember when i was a kid for a good while i had no idea qwilfish even existed, and here it is now getting a regional form and an evolution. whether you like qwilfish or not, you gotta respect how far it's come.