RB Golbat said:
Ground cause it hits many types supper effective and resists Bullet Punch.
Not really sure where I should've said this, but the untruthyness of this is apparent. :P
To be honest, if Water wasn't available as an option, Ground would probably be my choice, because of the Electric immunity Water only wished it had, built in resistance to Rock, supereffective on Tar, Heatran, Fidgit, and in some cases, Strata. Cool notice is that, if it was Ground, Strata's two advantages over it would be, for the most part, mutually exclusive. Giga Drain really wants Technician, but for that, it loses Ground immunity. Energy Ball is pretty much a nonfactor on most Stratagem, but, then, maybe CAP6 would change that.
Water's still a cool type, though, and some of the faults present with it could always be helped by secondary typing, movepool, and stats. Rock, high Attack, and a workable Speed could help it do a number on Zapdos and Pyroak... but that's getting really ahead of things.