illadelph12
aka Rakim Illa
Well, Surfer can survive the gravity well of black holes due to his design (he's designed to be able to cope with all of the dangers he may encounter in faster than light space travel, which makes him exceedingly durable), so he shouldn't have any issues.
Superman is likely ok as well.
Not sure how Thor's physiology would hold out from the strain as though he is an Asgardian he's also still flesh and blood. Not sure how his body would react to the strain. Even pumping blood would be a struggle.
I actually think Colossus would be fine given his organic metal make-up and the way his metabolism and organs change in his metallic form. He should be able to support his own weight even with the added gravity.
And before some simpleton rushes in here saying "Delph thinks Colossus is stronger than Thor", no, that's not what I'm saying. I'm saying that Colossus's physical make-up when in his armored form (fully metallic, no fatigue toxins, etc.) should make the strain easier to manage for his body than it would Thor's physical make-up.