Keen Smell. The beast dragon has advantage on Wisdom (Perception) checks that rely on smell.

Alternate form. The beast dragon can transform into a beast or monstrosity of any cr lower than its own. The beast dragon gains all the statistics of the creature except for their intelligence, wisdom and charisma scores and proficiencies. When they are reduced to 0 hit points or incapacitated in the alternate form they revert back their true form but on half hit points. They can go in and out of this form as an action.

Innate Spellcasting. The young beast dragon's innate spellcasting ability is Wisdom. The  young beast dragon can innately cast the following spells, requiring no material components:

3/day: jump

Multi attack. The young beast dragon  makes two claw attacks and a bite attack. 

Bite. Melee Weapon Attack: +7 to hit, reach 10 ft., 1 target. Hit: 15 (2d10 + 4) piercing damage plus 5 (2d4) cold damage and 5 (2d4) lightning damage. 

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit: 11 (2d6 + 4) slashing damage. 

Lightning blizzard breath (Recharges 5/6). The beast dragon exhales a blizzard like cloud which crackles with lightning, each creature within a 30ft cone must make a DC 14 Constitution saving throw or take 22 (5d8) lightning damage plus 20 (8d4) cold damage. On a successful saving throw a creature takes half damage.