Krilowatt is the epitome of versatility. It possesses the ability to be either a physical or special attacker, and it sits at a decently fast base 105 Speed, making it a solid sweeper. It possesses an amazing ability in Magic Guard, which blocks all indirect damage, and it has a solid defensive typing that leaves it with just 2 weaknesses. Couple that with its high 151 / 73 / 74 bulk, and Krilowatt is not easy to take down. It also has nearly perfect neutral coverage between its STAB and Ice-, Fighting- and Ground-type moves, being able to land neutral damage on every Pokemon except for Shedinja. Its options are not limited to all-out offense, either; it can effectively utilize many other sets to catch opponents off guard.
Although Krilowatt is a jack of all trades, it is a master of none. It often doesn't hit hard enough with only base 84 Attack and base 83 Special Attack, so it must hold a Life Orb to be used offensively. It also lacks reliable recovery moves, and has but a few status moves to take advantage of. Finally, despite the ability to fit multiple niches, it sometimes finds itself outclassed. Even so, Krilowatt is a solid Pokemon that can find a home on nearly any team depending on what is needed.
Surf is Krilowatt's reliable Water-type STAB attack, while Thunderbolt and Discharge provide it with Electric-type STAB moves. Thunderbolt has more immediate power, while Discharge has a higher chance to inflict paralysis, so both are equally viable choices. Ice Beam gives this set BoltBeam coverage and hits the Grass-types that pack a STAB move super effective against Krilowatt. Earth Power and Earthquake provide Ground-type coverage, which is super effective on many things that Krilowatt would normally only hit neutrally. Earth Power is optimal with a fully invested Special Attack stat, but an uninvested Earthquake hits specially defensive variants of Mollux and Heatran better than a fully invested Earth Power does.
Krilowatt can take advantage of Life Orb without receiving recoil damage thanks to Magic Guard; the item also shoots Krilowatt's low 265 Special Attack up to 345. Magic Guard also means that Krilowatt doesn't need to worry about taking damage from a status effect or entry hazards. A Timid or Naive nature is necessary to get the jump on base 100 Speed Pokemon; Naive is the preferred nature if Krilowatt runs Earthquake over Earth Power, as you don't want to lower its Attack stat. The EV spread is standard for a special sweeper, though the 4 HP EVs can be dropped into Attack if Krilowatt runs Earthquake.
Krilowatt is more of a fast late-game cleaner than a special wallbreaker, as its Special Attack is not great. You can, however, switch Krilowatt in at will without worrying about entry hazards or a stray Toxic or Will-O-Wisp. Even so, Krilowatt struggles mightily against special walls because of its inability to boost its Special Attack. Thus, you should try not to use Krilowatt until you eliminate all opposing special walls, as they can simply switch in and stifle momentum.
Krilowatt is a great standalone Pokemon, so you don't need to build your team around it. You do, however, need physical attackers such as Cawmodore or Azumarill to get past special walls. A teammate that can tank Ground- and Grass-type attacks is nice; most Flying-types work well in this role. Pokemon that appreciate Krilowatt's ability to tank attacks make good teammates as well. Aurumoth in particular appreciates Krilowatt's resistance to Flying- and Fire-type moves. Gothitelle is great at trapping and eliminating staples of stall teams such as Chansey.
Though most Krilowatt are special attackers, its base Attack stat is right on par with its base Special Attack. Waterfall and Thunder Punch are Krilowatt's primary STAB attacks, while both Ice Punch and Ice Shard provide powerful Ice-type coverage. Ice Punch has a much higher immediate power, while Ice Shard provides Krilowatt with priority. Finally, Earthquake and Low Kick provide great secondary coverage. Earthquake is often more reliable because it has a set 100 Base Power, but Low Kick will hit certain checks to Krilowatt such as Kyurem-B and Ferrothorn harder than Earthquake can.
Life Orb boosts Krilowatt's offensive presence, giving it an effective 347 Attack stat. Thanks to Magic Guard, it doesn't receive recoil from Life Orb. A Jolly nature is preferred to maximize Krilowatt's Speed. Alongside BoltBeam coverage, as well as a second STAB in Waterfall, choose Earthquake or Low Kick, depending on which coverage your team needs more.
This set has the role of a late-game cleaner as opposed to a wallbreaker, so Krilowatt should see limited use in the early-game. Additionally, Will-O-Wisp is a problem for this set because Magic Guard does not prevent the Attack drop from a burn. You should also keep Krilowatt off the field as long as you can because most opponents expect it to be running a special set.
Krilowatt is a great standalone Pokemon, so it does not need a lot of support. Special attackers can take on the physical walls that stop Krilowatt. Aurumoth, Volkraken, Stratagem, and Tomohawk work well in this role. Tomohawk has the added bonus of being able to switch in on the Ground- and Grass-type attacks that threaten Krilowatt. Aurumoth also has great synergy with Krilowatt and always appreciates Krilowatt's resistances to Flying- and Fire-type moves.
Krilowatt can effectively run Counter and Magic Coat due to its very high HP and comparatively low Defense and Special Defense. Trace is an option against foes with powerful abilities such as Tomohawk, but it is fairly matchup-dependent and inferior to Magic Guard. Heart Swap can be hilarious against an Aurumoth, Cawmodore, or Mega Slowbro that attempts to set up, but it is also extremely matchup-dependent. Still, a set of Waterfall / Thunderbolt / Ice Beam / Heart Swap with a spread of 20 Atk / 44 Def / 192 SpA / 252 SpD, Leftovers, and a Naive nature can guarantee that Krilowatt can steal a Cawmodore's Belly Drum and take advantage of the Attack boost before being KOed. Krilowatt can spread status with Toxic and Thunder Wave, but typically, stall-based Pokemon do that better. Additionally, Krilowatt struggles against most clerics such as Chansey and Sylveon, though moreso its special set than its physical set. Confuse Ray can be annoying to face, especially alongside Thunder Wave, but the move is very unreliable.
Checks and Counters
Dedicated Walls: Krilowatt is not a wallbreaker due to its somewhat low offensive stats and lack of a boosting move, so it struggles against dedicated physical and special walls.
Bulky Grass-types: Many bulky Grass-types can take an Ice Beam and retaliate with a super effective Grass-type move. In particular, Mega Venusaur and Ferrothorn are not hit super effectively by any of Krilowatt's attacks, save for Low Kick in Ferrothorn's case.
Fast Earthquake Users: Pokemon with a powerful Earthquake such as Mega Charizard X can deal serious damage to Krilowatt. Fortunately, most Earthquake users are weak to at least one of Krilowatt's coverage moves.
Setup Sweepers: Krilowatt often cannot deal enough damage to KO stat boosters before they begin their sweep. In particular, most Dragon Dance and Quiver Dance users, such as Mega Charizard X and Aurumoth, respectively, are naturally slower than Krilowatt, thus rendering Heart Swap useless against them. After becoming faster, they can potentially KO Krilowatt and then proceed to sweep your team.