requesting enemies headcanons for knock out and ratchet <3 (leaving it up to you if you wanna play this as “seriously trying to kill each other” enemies or just “prank war gone terribly wrong” enemies)
Knock Out is the primary instigator in their antagonistic rivalry. Any time he even thinks Ratchet might be listening, he is spewing out any insult he can think of to get a rise out of him. His success rate is surprisingly high because despite how petty his remarks are, Knock Out knows exactly what to say to get under Ratchet's plating.
Ratchet's primary form of combat for Knock Out is out right ignoring him. Its success rate is about 50/50 whether Knock Out is going to read it as cowardice on Ratchet's part or take it as being ignore (the thing he probably would hate most after his finish getting destroyed).
They are also both pretty bad at physically fighting each other. Ratchet's movement is not where it used to be and Knock Out hates the idea of risking his paint job by getting to close. So its mostly just mean words flung back and forth while Bulkhead and Breakdown beat the slag out of each other (essentially as a proxy).
This doesn't get better when Knock Out becomes an Autobot, but the level just goes down to petty coworkers. It's more annoying than malicious but Ratchet and Knock Out act as if it is an all out war of their basic rights. Whoever is leading the Autobots at this time is very exhausted with their complaints.
Their truce only ever ends temporarily when some poor, unsuspecting Autobot does something to piss both of them off. Then that poor mech has the face the wrath of two bitter, snappy medics. They almost allow it to bridge their friendship but inevitably, one of them (Knock Out) pisses the other off again.