You're missing Octane. (Ducks)
I was targeting all the Decepticons we actually saw serving under Megatron's command during G1. I mean, we could assume every Decepticon served under him at some point, but just focusing on the ones we actually saw. So, all the '84-'85 toyline (including Reflector, since Takara did sell him in '85 even if Hasbro didn't), plus Menasor and Bruticus since they showed up in both the cartoon and comic, and Ratbat since he was there for the battle at Autobot City. I was tempted to try to fully include the comics too, since I think I'd only need to add Runabout and Runamuck to cover the US run, but I don't think I can fit even just those two in, much less guys like Octane from the UK run.
Oh, and I'm ignoring his Action Master revival. It really felt like a separate thing even at the time, the new AMs don't have matching modern updates, and I always head-cannoned the new-character AMs as being Gutcruncher's band of mercenaries that were working with Megatron, but weren't really his followers. My way of interpreting Gutcruncher's rank of 10.