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., hearing, or smell.
Magic Resistance. The pseudodragon has advantage on saving throws against spells and other magical effects.
Limited Telepathy. The pseudodragon can magically communicate simple ideas, emotions, and images telepathically with any creature within 10 ft. of it that can understand a language.
Sting. Melee Weapon Attack: + 5 to hit, reach 5 ft., one creature. Hit: (1d4 + 3) piercing damage. The target must succeed on a constitution saving throw DC 12, or become poisoned for 1 minute. If the saving throw fails by 5 or more, the target falls unconscious for the same duration, or until it takes damage or another creature uses an action to shake it awake.
Bite. Melee Weapon Attack +4 to hit, reach 5 ft, one target, Hit: 4 (1d4+2) piercing damage plus 1d4 lightning
Familiar. This pseudodragon serves you as a familiar, forming a magic, telepathic bond with you. While you two are bonded, you can sense what the pseudodragon senses as long as you are within 1 mile of each other. While the pseudodragon is within 10 feet of you, you share the pseudodragon's Magic Resistance trait. If it dies then you may expend a 1st level spell slot to revive it again. At any time and for any reason, the pseudodragon can end its service as a familiar, ending the telepathic bond. However, if you revived it after dying it will merely stay away for (usually) 8 hours before approaching you again. As an action, you may summon your Pseudodragon to appear within 5 feet of you, if it is willing.
Counterspell. If the attack deals lightning damage, the spell is reflected back at the caster.