Who can defeat Superman, The Hulk, and Silver Surfer?

who can?

At the same time? Doomsday

Kal Kent

Gold Experience Requiem's ability is to turn anything, including his opponent's attack and willpower, back to the state of "zero". Hence, it is near invincible, as all "supposed" actions created by an opponent would have been reset (back to point zero). If the opponent is killed by the Stand's attack, then they will also continuously experience death, as they will die but repeatedly return to point "zero".

Galactus, Odin, Zeus, Thanos, Thor (Odinforce), Living Tribunal, Stranger and others.

Highfather, Darkseid
Thanos, Odin
Galactus, AM
need i go on

"At the same time? Doomsday"