He provides built-in card draw and token replacement, which makes Zombie decks smoother, more resilient, and easier to pilot across casual and mid-power Commander tables
Three decks is still a good number, variety wise, as it lets you bring say a Precon, a Bracket 3 deck, and then a Bracket 4 or cEDH deck
I say should because Doctors Companion, the partner mechanic for the Doctor Who set, specifically cares about a card being a Time Lord Doctor while having Doctor in the Legendary Creatures name
These are not to be confused with proxies, cards used as stand-ins for the real thing for the purpose of testing or to keep valuable cards out of decks and safe
One of the perks of playing a combat trick that does two things it gives you multiple ways to interact with the board
Unfortunately, ramp is the kind of strategy that is either going to be great or horrible