Brachiosaurus

Trample. The brachiosaurus can share the same space with creatures that are large or smaller. Any creature that starts its turn in the brachiosaurus' space must make a DC 20 Dexterity saving throw, taking 7(2d6) bludgeoning damage on a failed save, or half as much damage on a successful one.

Sure-Footed. The brachiosaurus has advantage on Strength and Dexterity saving throws made against effects that would knock it prone

Multiattack. The brachiosaurus makes two attacks: one with its stomp and one with its tail. It can't make both attacks against the same target.

Stomp. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 26 (4d8 + 8) bludgeoning damage. If target is a creature, it must succeed on a DC 20 Strength saving throw or be knocked prone

Tail. Melee Weapon Attack: +12 to hit, reach 20 ft., one target. Hit: 26 (4d8 + 8) bludgeoning damage.