Kingler

Hail to the King! Kingler has fairly high Atk, higher than that of Gyarados. At its release, this attack stat was largely ignored due to Kingler's poor moveset However, the addition of Crabhammer gives Kingler the moveset it needs to out-DPS a number of the older kings of the type, though this comes at the cost of some TDO. In a nutshell, Kinger can be viewed as a glass cannon Water-type Gengar. With a little bit of dodging, Kingler can be a very strong contender.

Best PvE Offensive Moveset

• Bubble is Kingler’s best fast move, letting it function as an offensive Water-type.

• Metal Claw and Mud Shot* lack STAB and are not nearly as good.

• Crabhammer is Kingler's best charge move, and mandatory for optimal DPS. 

• Razor Shell is clearly superior to Water Pulse, X-Scissor, and Vice Grip due to STAB. But it also falls behind Crabhammer by a fair bit.

Best PvE Defensive Moveset

• Bubble is Kingler’s only fast move with appreciable defensive DPS.

• Metal Claw is good for its synergy with Kingler's best defensive Charged Moves, while Mud Shot* does Kingler no favors.

• X-Scissor is a 3-bar charge move that is hard to dodge and covers Grass-types.

• Vice Grip has similar properties to X-Scissor, but it is weaker and Normal-type.

• Razor Shell has great stats, but pairing it with Bubble leaves Kingler easy to pick off for anything that preys on Water Types.

• Crabhammer is Kingler’s strongest charge move, but is easier to dodge.

• Water Pulse is inferior to Crabhammer in every way. 

Mud Shot is a legacy move, but offers the best energy generation in the game. Bubble takes advantage of STAB to deal significantly more damage than Mud Shot, with still respectable energy gains.

X-Scissor is generally a weak move, but demanding the least amount of energy and providing coverage against Kingler's weakness to Grass-types can be valuable. It's also the best option for baiting shields. Crabhammer benefits from STAB to deal very respectable damage, and is a direct improvement over Water Pulse.