Undead Fortitude. If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie drops to 1 hit point instead.

Skulking Dead. Stealth remains an almost instinctive response for the zombie.  It can take the Hide action as a bonus action on each of its turns. 

Undead Nature. The zombie doesn’t require air, food, drink, or sleep.

Slam. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage.

Flying Tackle. When attacking a medium or smaller creature the zombie has advantage against, the zombie makes an opposed Athletics checks with advantage to grapple.  If successful, it knocks enemy prone and makes two Slams attacks with advantage.