I concur that Thundurus is awesome. It has the coverage in TBolt and HPIce and the speed and special attack to back them up, shuts down set up with Taunt, and cripples fast sweepers with TWave. It and Blaziken are usually my MVPs.
Dragonite (with Multiscale) and Garchomp are also rather effective. You can also just go with the standard rain team, which for some reason is rare on Wifi even though it rips apart most teams. Same goes for Trick Room.