Barbaracle
Super Mario Boards
Green Mage
I don't think i've ever had a specific least favorite, but Ledyba clogged up my camps in Mystery Dungeon DX so I guess I'll go with it
Kong Rong
i'm glad @Hooded Pitohui has finally come off his Igglybuff hate
Specture Striker
Pineco, LITTERALLY just a pine cone, it barely has anything interesting to its apperance, its evolution makes NO sense, and is just a waste of a desgin, like come ON you could have put SOME effort into it, like make it have more sharp spines or take insperaration from different types of pine cones! like SOMETHING come on.
Koopa
I dunno. Which one is your favourite?
kidding don't kill me
Once I would have answered Gurdurr, but my antipathy towards Lickilicky continues to grow. Lickitung is soooo cute and manages to make its main fantastical feature work well with a coherent animal-lick design. Then Lickilicky comes along and throws all of that out for no good reason! That thing doesn't look like a critter.