Reflective Carapace. The baby Tarrasque has yet to develop the thick hide it's parents are so well known for. It's scaly skin feels soft to the touch.

Multiattack. The baby tarrasque can use its Adorable Presence. It then makes five attacks: one with its bite, two with its claws, one with its horns, and one with its tail. It can use its Swallow instead of its bite.

Bite. Melee Weapon Attack: +19 to hit, one target. Hit: the baby's teeth have yet to grow so it softly gums it's enemy. 

Claw. Melee Weapon Attack: +19 to hit, one target. Hit: The claws, similar to the teeth, aren't properly formed and being hit reminds you of a massage a Tabaxi gave you.

Horns. Melee Weapon Attack: +19 to hit, one target. Hit: Being gored by a baby tarrasque is like being punch by a cloud.

Tail. Melee Weapon Attack: +19 to hit, one target. Hit: Mhmmm... Exfoliating!

Adorable Presence. Each creature of the tarrasque's choice within 120 feet of it and aware of it must succeed on a DC 17 Wisdom saving throw or become charmed for 1 round. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the tarrasque's Adorable Presence for the next 24 hours. 

Swallow. The baby tarrasque gums the end of your arm, gags and spits it out.