Just to establish Omega's place on the food chain compared to your typical gestalt:
Megatron, after a good fight, defeated Predaking. His fusion cannon dropped him easily.
Yet when he lead an attack on the ark, he and about a dozen or so cons couldn't even scratch Omega's tank component. Omega tore through the assault squad, laid out Megatron with a single hit of his claw arm, and would have finished him off if Laserbeak didn't fly him away.
That said, laughing off Megatron and an armies worth of weapons is a common feat for UK Galvatron, the Thanos of Transformers.