If you are specifically looking to do zombie tokens, Moan of the Unhallowed
is decent, made better with parallel lives and can flashback as well.
Death Baron is pretty expensive, if you have the budget then go for it. If not I feel Cemetery Reaper
is a decent substitute. Still buffs, and can even help with token generation and removal from opponents graveyard if they like to bring stuff back. Army of the Damned
might be feasible if you have enough ramp. Green has plenty of ramp, if you are looking for some black ramp there is Llanowar Dead
As for beefy creatures, obviously there are tons of beefy green creatures and black has its fair share, but if you are looking to stick strictly with the zombie theme then Grave Titan is your best bet.