A solid team, just a few suggestions.
-Golem should not use Return. Give it something more useful, like Sucker Punch. Return really gives nothing. I also always like putting those last EVs into HP over other defensive stats.
-Rotom is missing 4 Evs. Also, I always suggest HP Grass on it because otherwise Golem will screw it over completely. So I would replace Signal Beam for HP Grass.
-Cradily gets Giga Drain from the BW2 Tutor, making it legal with Storm Drain. So go with that, as five less base power is made up for with healing.
Other than that your team is good. The Pokemon work pretty well together, so besides a few things to improve the Pokemon, your team should be running good.