[@Holy Soldier]
But unlike Link those are absolutely completely different beings from series to series with completely different power-sets and different types and levels of technology involved.  Disregarding the difference between Rock and X (and the fact that X is more of Rock's brother who later became a Cyberelf in Zero and then there is Copy X who is his clone), Volnutt is a hyperadvanced human-like android far past the Zero and ZX timelines.  The ZX timeline itself has personalities of Zero-timeline beings such as X and Copy X (and sort of maybe Rock himself) stuffed into hypertech henshin devices.  Mega Man Battle Network is a parallel timeline where Rock is a Tron-style program with a twin human brother who he sometimes merges with.  Like X there is a later not-Rock named Rock who [i]also [/i]is able to merge with a human (who is the EXE's twin's descendant) but this is how Mega Man is formed in that point of time.

Then there's the Evil Timeline Megamen we have Quint and Rockman Shadow.  Evil copies of Megaman such as Mega Man? and maybe Shadow Mega Man.

If we include all the other Mega Man named character we also have Juno in Legends and all the other Biometal users in ZX.

I do understand about fusing different versions of the same character together but these are different beings altogether.