Axiom Nexus has rules about this sort of thing.
Very important rules.
Rules you don’t ignore if you want everything to keep spinning and throbbing, and pulsing, and doing whatever it is things do to keep simply existing.
Of course that doesn’t stop the things that would infringe those rules from actually showing up. The cities defenses are usually enough to keep them at bay. The usual Optimus you can generally ask politely to please turn around and return to his home dimension or at least one adjacent, They almost never end up in the Axiom city limits intentionally and are happy to move along.
The Megatrons however?
Well they’re all pretty much the same, always seeing the city as an excellent a foothold in their eternal war, blah blah yadda yadda.
Fact is, when it comes to them and their persistence, we’re glad they only ever show up one at a time, because the city defenses only hold out for so long. And when they don’t it becomes necessary to employ outside contracts.
Due to the ever tangential nature of the multiverse holding ‘contracts’ with people across existence is… Difficult at best. Not simply because lines of communication across the Quixotic can be severed by realignments or the occasional ceasing of existence, but the only people who can actively receive and send messages across dimensions are they themselves a jangled mess of chaos.
So when we called for aid this one time and a small pink member of the genus Equus showed up… We tried VERY hard not to be surprised.
But not being surprised went right out the proverbial window when she somehow managed to get Megatron (U# 33445), to sing Christmas carols.
Seriously we watched the feed the whole time, we have no idea how she did that.