Who said an RU Pokemon can't run with the big boys?
So just now I was using Accelgor in Ubers, yes you read that right, Ubers. I have found that he is amazing in Ubers, thanks to the fact that his typing and stellar speed allow him to outspeed and cut down common threats such as Darkrai, Mewtwo, and Extremekiller Arceus with STAB Bug Buzz and Focus Blsat respectively. He is also capable mowing through the many Uber dragons with relative ease thanks to Hidden Power Ice.
ACC3LGOR @ Choice Specs
Trait: Sticky Hold
EVs: 252 SAtk, 252 Spd, 4 Spdef
Hidden Power [Ice]
I can not stress how well he really does work in Ubers. His outstanding speed allows him to outspeed most unboosted opponents, and Choice Specs gives him some firepower, boosting his SAtk up to 492. Choice Specs, plus his great speed allow him to bring punishment as a revenge killer and as a late-game sweeper. As I said previously, his main role is to check things like Darkrai and Mewtwo that could otherwise pose a threat.
P.S. This set greatly appreciates entry hazard damage, but it is not neccessary.
P.S.S. This set is not limited to Ubers, it works in well in other tiers too.