Keen Hearing and Smell. The Totally Normal Dog™ has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Unwavering Loyalty. The Totally Normal Dog™ will always follow the commands of an NPC or PC that they have a positive relationship with.

Alert. The Totally Normal Dog™ can't be surprised while conscious and other creature's don't gain advantage on attack rolls against him as a result of being unseen by him. The Totally Normal Dog™ has +5 to initiative. 

A Totally Normal Dog™. The Totally Normal Dog™ is capable of most things a PC can do (climb, intimidate, stealth, etc) but with disadvantage on anything that would be difficult or impossible for a dog to do. The Totally Normal Dog™ does not have disadvantage on the following skills: Arcana, Athletics, Insight, Intimidation, Investigation, Nature, and Perception.

Tricks. The Totally Normal Dog™ is a unknown level spellcaster. Its spellcasting ability is Charisma (spell save DC 19). The Totally Normal Dog™ knows the following tricks (that you have discovered):
Sit: The Totally Normal Dog™ sits.
Come: The Totally Normal Dog™ casts Teleport on itself to move direct next to the person who issues the command. The Totally Normal Dog™ can take up to 8 willing creatures with it so long as he can see them and they are within range. (1 / Long Rest)
Shake: The Totally Normal Dog™ casts Earthquake. (1 / Long Rest)
Heel: The Totally Normal Dog™ casts Cure Wounds at 2nd Level on the most injured party member within range. (3 / Long Rest)
Speak: The Totally Normal Dog™ casts Speak with Animals on itself. In addition to the spell effects, it removes disadvantage from all rolls involving speech. (3 / Long Rest)

Goodest Boi. On The Totally Normal Dog's™ turn, a PC or NPC can command the The Totally Normal Dog™ to either Bite or complete 1 trick from the known trick list.

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: (1d6 + 1) piercing damage. If the target is a creature, it must succeed on a DC 12 Strength saving throw or be knocked prone