I me
I think giving Bowser everything in mainline that’s not Dreamy Bowser (since it’s a form he only gains by accident with an artifact he gains in the last hour of the game lol) is fair game, and at that point even with his highest stats Eggman still has every other advantage. Even if you assume equal stats, Metal Virus would ravage Bowser’s entire army and turn it against itself, turning even basic Goombas and Troopas into life ending threats for Bowser and his other troops, Sage shuts down all of his tech options, and Eggman has like 4-5 different “strongest mechs” while Bowser only has one “strongest” state, himself. Meanwhile Eggman has the Phantom Ruby for subterfuge and ensuring his safety, Time Eater could realistically just cosmology wipe Bowser and his troops out of existence, the rest of their haxx goes back and forth. etc
even with Dreamy Bowser he’d still lose as he’d still run into all the exact same issues he’d have without him (and Dreamy Bowser wouldn’t even really matchup to the strongest levels of power in sonic anyways due to translational inconsistencies and such)