I bet The Doctor could have beaten Colossus.... All he's have to do is go to those huge doors aim the sonic screwdriver and open them and bring down the radiation field just like that remote control they conveniently lost......
Or use the TARDIS beam into the Computer and go hack hack hack with something sharp...
The Doctor probably could have handled the situation by dropping by in the TARDIS and having a chat with Colossus. Poor Colossus would likely not stand a chance at all.
But, as a last resort, he could tell it what happened to the Slitheen or the Nesteene Consciousness, then give Colossus a chance.
Woman: Harriet Jones, Former Prime Minister. Doctor: Yes, I know who you are. Harriet: Doctor, are those shooting stars? Doctor: No. Those are pieces of the Enterprise burning up in the atmosphere. Rose: So we're getting ash instead of snow? Again? Doctor: It wouldn't be Christmas in England without ash, now would it? Harriet: I did not order Torchwood to do that. Rose: So who destroyed the Enterprise? Was it the Daleks? Doctor: No, something far more dangerous. Colossus. Harriet & Rose: We're doomed, then! Doctor: No, I used the sonic screwdriver to turn Colossus into a Commodore 64. Harriet: My Doctor! Rose: Hands off! My Doctor! Woman: Doctor, are you coming back to the TARDIS? I'm lonely! Harriet & Rose: Who is that? Doctor: Oh, it's just a Kissogram I received for my 954th birthday. [TARDIS engine sounds] Harriet: Well that was rude! Rose: You get used to it. Um … fancy a nightcap? Harriet: Certainly. My flat's right over there. Rose: Perfect! Let's have some fun! Harriet: Yes! I can even show you my subwave network. Rose: I'll bet you can, you naughty Former Prime Minister you!