X-Men
Which X-Men can defeat the T-1000?
I'm guessin iceman can freeze it then the others can take care of it.
Or magneto can lift it and drop it in a volcano or fire pit
Oh boy, I love these fictional nerd fights :)
Let's see, aside Iceman and Magneto that you mentioned, the following characters would be strong candidates to win.
Cyclops or Havok
Either of them could keep blasting T-1000 apart with his concussion beam or plasma blast until T-1000 starts suffering from some kind of malfunction. This might take a while.
Most of the time Cyclops' beam is described is specifically depicted as a concussion beam, not laser, but assuming Cyclops' beam can melt stuff, that's also bad news for T-1000. Ditto for Havok's plasma blasts.
Cable or Jean Grey
He/she could use her telekinesis to blast T-1000 apart on a molecular level.
Storm
Blasting T-1000 with a lightning would most likely cause it to malfunction.
Kitty Pryde
Kitty's phasing powers can screw up electronic devices.
Nightcrawler
Nightcrawler could teleport a part away of T-1000 which would at the very least significantly slow it down. However, this would require close proximity and split-second timing, which would be extremely dangerous.
Gambit
Gambit could blast T-1000 apart by charging it with kinetic energy. However, this too would require both close proximity plus few seconds, which would very likely prove fatal to Gambit assuming he's fighting T-1000 by himself.
Banshee
The strength of Banshee's supersonic scream varies depending on the source, but it's likely that he could do significant damage to T-1000 with it.
Forge
Forge would invent a super-duper remote controller that would shut T-1000 down. Or an EMP-cannon. Or something :D