Here's how Optimus and Megatron's battle goes in Ed, Edd, n Eddy vs. The Mummy: Tomb of the Dragon Emperor.
[Megatron is sneaking up behind our heroes. Then he is hit by a blast]
Megatron: Uh! [looks back. And it shows that it was Otpmis] Optimus?
Optimus: YOU TRIED TO HAD BRIAN, THOMAS AND HIS FAMILY KILLED!! [does another force blast]
Megatron: Yes I did. Thomas fialed me to kill Celestia, I could do the same to all of them! If that saddle back engine didn't come in my way, they could have lived! [fires his shotgun]
[Soon the 2 tackle and Optimus is clashing his energy axe, while Megatron is using his sword]