Uber: Dragon and Psychic by FAR
OU: Psychic, Dragon, and Steel types are by far the most common. Fighting types are pretty common too. Water and Fire types are also rather common.
BL/UU: Fighting, Water, and Ground types are everywhere. Flying, Electric, and Steel types are also pretty frequent.
RU: Bug, Flying, and Rock Types, Water and Grass are pretty common too.
NU: Bug, Grass, Ice, Normal, and Water are the ones around here, pretty much the ones that are are under-powered.