The Pokémon no one ever remembers? I'd have to say Mothim. It's useless in battle, not easily obtained and its design (although I must admit it's quite cute. :3) is too similar to Butterfree's and Beautifly's for it to truly stand out and as sad as it is, both of the Pokémon I just mentioned also happen to outclass Mothim in terms of battling. That, and I've never seen anyone mention the Pokémon.
Wailord. It's quite strong actually.
The only thing there is to fear from Wailord is a Choice Scarfed Water Spout; it's base stats are simply horrible and the movepool is less than impressive. A cool Pokémon, but not really that strong. =\
Dunsparce has like no good moves, and they haven't even evolved it, if they make another game I think they should evolve it into a dragon.
No good moves, you say? Allow me to list all the notable moves Dunsparce has access to
and can effectively use: Body Slam, Rock Slide, Headbutt, (see the comments after this for a clarification) Counter, Roost, Charge Beam, (although it's a bit of a gimmick move for 'Sparce) Magic Coat, Yawn, Screech, Ice Beam, Flamethrower, Thunderbolt, Thunder, Calm Mind and Thief (a bit of a gimmick as well, but can be a nasty surprise for some walls). Now, Dunsparce's stats may not seem that impressive, but 100 base HP is enough to let it survive hits even from some of the stronger sweepers in the game and Dunsparce's ability, Serene Grace, doubles the odds of getting an added effect from moves, which boosts Body Slam's and Thunder's paralysis rate and Headbutt's and Rock Slide's flinch rate up to 60% which makes a paraflinching Dunsparce a force to be reckoned with, especially considering that few things that aren't unboosted STAB Fighting type moves can OHKO a properly EVed Dunsparce. I've stopped several 2x Attack boosted Gyaradoses and Garchomps with my Dunsparce in Shoddy and both times, it saved the game for me.