Empoleon

While several other Water-types remain better, the addition of Community Day Hydro Cannon puts Empoleon on equal footing with Feraligatr, despite a few differences with its defensive typing.

This prideful penguin is the only starter ever to boast the useful Steel secondary typing, which gives it as many as 11 resistances, as well as an undesirable weakness to Fighting. This secondary typing notably makes it stronger against Rock-types, though makes it weaker against Fire and Ground-types, Water's two other super effective uses.

Best PvE Offensive Moveset

• Waterfall and Hydro Cannon* make Empoleon a viable Water-type attacker. Hydro Pump is an unexciting replacement to the Community Day exclusive move and is noticeably weaker.

• Metal Claw with Flash Cannon counters Fairy-types, but it’s underwhelming.

• Steel Wing is worse than Metal Claw..

• Blizzard, Flash Cannon, Metal Sound, and Drill Peck have little to no use on Empoleon.

Best PvE Defensive Moveset

• Waterfall out-paces Steel Wing, Metal Sound, and Metal Claw on defense.

• Hydro Cannon is an optimal choice for damaging attackers.

• Drill Peck can be spammed frequently as a 3-bar move, and is also great against Fighting-type attackers. 

• Hydro Pump is stronger than Flash Cannon; both can be hard to dodge.

• Blizzard probably won't get a chance to launch, but it can severely maim many common gym cleaners like the big-name Dragons.

Metal Sound offers the best energy generation, allowing Empoleon to reach its potent Charged Attacks quickly. Waterfall and Steel Wing's energy generations are below average, and Metal Claw is strictly worse than Metal Sound

Hydro Cannon is one of the most powerful charge moves in the game, and is necessary not only for its high DPE value, but also due to its significantly less energy cost. Drill Peck ties for the cheapest charge move energy-wise, which is important as Empoleon's bulk is middling. It also provides useful coverage against its vulnerability to Fighting-type Pokemon. Flash Cannon benefits from STAB and is cheaper than Blizzard, but the latter provides significantly more valuable coverage. Neither of these two moves are recommended due to their expensive energy costs.