Beefy zombie

Undead Fortitude. If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of the damage taken divided by 2, unless the damage is from a critical hit. On a success, the zombie drops to 1 hit point instead.

Hoard tactics. if an ally is within 5ft of the zombie's target then it gets advantage to knock the target prone/unconscious.

Slam. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 11 (2d10 + 1) bludgeoning damage. on a hit, the zombie has a 1 in 6 chance to knock the target prone, and a 1 in 12 chance to knock the target unconscious (they can be awoken as an action)

Bite. Melee weapon Attack: +4 to hit, +8 if the target is grappled,  reach 5 ft, one target,  hit: 16 (2d12+4) piercing damage.  if the target is a creature it must make a DC 14 con save, if the target has been subject to this attack previously then DC goes up by 1. on a fail the target is afflicted with zombie rot.  a target afflicted with zombie rot takes 1d4 necrotic damage every 2 minutes. if the afflicted target ever drops to 0 hit points, they turn into a zombie.