Runic mute. Since a chole dragon has runes covering its body that allows it to cast spells and have the extra tentacle appendages the price is that they may never vocalize making them effectively mute. 

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Tentacles. The chole dragon has a random amount of tentacles determined by 1d8 this number doesn't decrease or increase as they age but does determine their innate spellcasting. 1-2: four tentacles, 3-4: seven tentacles, 5-6: nine tentacles, 7-8: thirteen tentacles. 

Innate Spellcasting. The adult chole dragon's innate spellcasting ability is Wisdom (DC 18, +9 to hit with spell attacks). The adult chole dragon can innately cast the following spells, requiring no material or verbal components:

four tentacles: 3/day: fly (self only), vampire touch 

1/day: magic circle (only effects lawful creatures)

seven tentacles 3/day: darkness, slow

1/day: fly (self only)

nine tentacles 3/day: fireball, levitate (self only)

1/day: dispel magic 

thirteen tentacles 3/day: magic circle (only effects good creatures), mirror image

1/day: haste 

Multiattack. The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws or makes how ever many tentacle attack it has tentacles for or makes a bite attack and two claw attacks. 

Tentacle. Melee Weapon Attack: +6 to hit, reach 20 ft., 1 target. Hit: 4 (1d8) bludgeoning damage. 

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., 1 target. Hit: 19 (2d10 + 8) piercing damage. 

Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., 1 target. Hit: 15 (2d6 + 8) piercing damage. 

Tail. Melee Weapon Attack: +14 to hit, reach 15 ft., 1 target. Hit: 17 (2d8 + 8) piercing damage. 

Frightful Presence. Each creature of the dragon's choice that is within 120 ft. of the dragon and aware of it must succeed on a DC 20 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.

Insanity gas breath (Recharges 5/6). The chole dragon exhales insanity vapors, each creature within 60ft cone must make a DC 21 Wisdom saving throw or have their Charisma or Wisdom stats reduced by 1 (which ever is higher) and also make a DC 21 Constitution saving throw or take 65 (10d12) poison damage. On a successful save a creature takes half damage and the stat reduction can be reversed by a creature taking a long rest (1 point regained per long rest). 

The adult chole dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time, and only at the end of another creature’s turn. The adult chole dragon regains spent legendary actions at the start of its turn.

Detect. The dragon makes a Wisdom (Perception) check.

Tail Attack. The dragon makes a tail attack.

Insanity pulse (Costs 2 Actions). The chole dragon lets out a pulse of abyssal energy and each creature within a 60ft radius around the chole dragon must make a DC 21 Wisdom saving throw or be under the effects of the confusion spell until the end of their next turn.