Morg is pretty much Terrax level. Terrax and Firelord alone without jobbing has given Surfer fits. If they double team Surfer, the fight is done. Star Dust is pretty much Firelord level with high end durability but having these type of Heralds double teaming him isn't good.
The team wins 10/10 and they win it without too much trouble. Some of these people alone has the power output of a high Herald.
Firelord and Morg as a team can pull some wins...at least 2 or 3 if they play their cards right...any other type of help is ludicrous.
Seriously though when Galactus resurrected Morg after the WOL incident he went to get his axe back from Terrax and beat him down and would have killed him only them being captured by Tyrant stopped him.When they were freed another fight started and Morg beat him again.
And the second time around, they fight again during the time the heros was fighting Tyrant and they stalemated and Terrax had the upper hand against Morg.
Morg has beaten Terrax twice Surfer once and both Firelord and Airwalker his record speaks for itself Terrax having a good showing against him does not in anyway mean that Morg is on his level he is much closer to Surfer in power than he is to Terrax.
I am pretty sure the fight you are referring to is when they fought and Morg was mind controlled.