Blastoise

Amphibian: Can breath under water and on land.

Natural environment: when in water or heavy rain blastoise may dash using it bonus action and may use its swim speed.

Multiattack: blastoise can make 2 attack per action, 2 tackles, a tackle and bite, or 2 bites.

Tackle: +2 to hit,5ft range,1 target, 14 (2d6+2) bludgeoning damage

BITE: +2 to hit, 5ft range 1 target, 10 ( 1d10+2) Piercing damage 

Hydro Pump: +5 to hit, 30ft cone range, all in range, 20 (3d10) cold damage

Scald:+5 to hit, 60ft range, 1 target, 8 bludgeoning+6 fire damage (2d8 bludgeoning+1d8 fire) damage

Rain dance: as a bonus action Blastoise will shoot his canons in the air and a 120ft area is cover in heavy rain for 3 rounds. Blastoise cannot use hydro pump or canon on the same round it used rain dance.

Withdraw: if stuck by an attack Blastoise will withdraw into its shell raising its ac to 24 but has disadvantage on dex and str saving throws. It takes a bonus action to come out of withdraw. You can only take a 10 ft movement action while withdrawn.

Blastoise gets 3 legendary actions per round.

Hydro cannon: (3 actions) Blastoise shoots out a large torrent of water out of it cannons: range 120 straight line, anyone in the stream needs to pass a DC 18 DeX Save or be pushed back 120 feet and take 10D10 cold damage. Success save negates damage and is not pushed. If target cannot be pushed the full 120 due to a obstruction then they take 1d6 bludgeoning damage for every 10ft that they didnt travel. After using this legendary action blastoise is stunned till the end of its next turn.

Surf: (1 action) Blastoise summons a wall of water that's 30 feet wide and 15ft high  travels 20 feet, targets caught must pass a Dc 15  strength check or be pushed back to the 20 ft and knocked prone. Successful save negated push and prone

Protect: (1 action)If blastoise fails a saving throw he instead passes it.