(shit, three posts? I didn't mean to type this much.)
Zero, as a reploid, has a survivability that only personnel with RED (is that the term?) or being put in a nannybag can muster. Zero has directly survived events that most would consider suicidal; to use just one example, Zero was at ground zero of an explosion that devastated a human residebtal district-having ridden the missile in question to its destination. Zero is well known for his sheer unkillability - being seemingly destroyed during Sigma's first uprising and the Eurasia crisis, Zero was able to be repaired (seemingly possessing a self-repair capability of his own in the latter case) from the catastrophic damage. Zero's contemporary, Mega Man X, was able to turn himself into a cyberelf, that proved capable of persisting after the annihilation of his physical self, only expiring after expending all his energy roughly a year later. If Zero can somehow manifest this capability, perhaps with the aid of our research team, even the total destruction of his physical form may not kill him, instead leaving him incorporeal until we can replace his body. Even then, we could replace the inferior copy of his form with a replica of his body as it was originally designed by Dr. Wily, if our replicators are good enough (probably necessitating upgrades to the replicators, from their present level, but that will come in time), increasing his effectiveness.
And that's pretty much my reasoning for the nomination. just putting it on the record, now let's get back to vampire slaying.