[Mick Gordon's "The Only Thing They Fear Is You" intesintesifies]

Chances are Samus would be able to kill them with plasma and/or ice, from disintegrating them or freezing+shattering them.

Master Chief might have a bit of trouble switching from ranged to only melee, but he should be fine with an energy sword.

Doomguy, as we can see, has no issues whatsoever.

Isaac is probably happy as hell that he can finally just sit back and be a smart, non-action oriented engineer again.