Round One: T-1000, returning to his apartment, notices a bottle of green fluid on the coffee table. "Oh, boy!" he says. "Gatorade!" He gulps it down.
Round Two: Inside T-1000's tummy, Odo partially solidifies. He thrusts his arm up T-1000's throat and out his mouth, then tries to strangle him.
Round Three: T-1000 liquefies. So does Odo. They pour into each other, squishing together in a huge, disgusting glob. Odo attempts to boot T-1000 in the kidney, but inadvertently kicks his own @$$.
Round Four: With a grunt, they pull themselves apart. Odo resumes his humanoid form. T-1000, still liquefied, slithers under the kitchen door.
Round Five: Odo bursts into the kitchen. No sign of T-1000. There are, however, a pair of sunglasses in the sink. Odo smiles. He liquefies and dives down the drain.
Round Six: It's a trap. T-1000, who had disguised himself as a toaster, shapeshifts back into a humanoid and flicks on the garbage disposal.
Later: T-1000 calls a plumber to ream the goo out of the pipes and then kills the plumber when he's finished.
Winner: T-1000