While Slaking boasts immense physical strength, a phenomenal movepool, and excellently distributed stats, he is severely hampered by his ability, Truant, which causes him to be idle every other turn. Because of this, Slaking performs best when holding a Choice item, as it allows him to make the most of his discrete turns. Generally, Choiced Pokemon require some level of prediction to be used successfully, but this requirement is of far greater importance when using Slaking. Bringing Slaking onto the field is a huge gamble, and it will almost always result in a casualty; whether it is Slaking's or your opponent's, however, depends on who made the right move.
Slaking exhibits great distinction as a physical sweeper because of his herculean base 160 Attack (the third highest in the game) and quick base 100 Speed. Coupled with an unbelievably wide movepool, a hefty amount of bulk, and the power boost from Choice Band, Slaking will be flattening opposing teams in no time.
STAB Return coming off 690 Attack is no joke at all, and it OHKOes a great number of Pokemon, while at the very least 2HKOing every Pokemon that doesn't resist it. However, using it randomly in the hopes of hitting an opponent hard is not recommended, as Slaking's ability firmly punishes any misplays. Instead, you should initially have Slaking scout with a coverage move to keep your opponents on their toes. Earthquake hits Rock- and Steel-types that resist Return very hard, 2HKOing the standard Steelix and Regirock, as well as OHKOing Registeel with Stealth Rock and two layers of Spikes on the field. Fire Punch also hits Steel-types super effectively, and although it is not as powerful as Earthquake, it also OHKOes frail Levitating Ghost-types such as Mismagius and Rotom with Stealth Rock support. In the final slot, Slaking has two promising options in Shadow Claw and Pursuit. The first is a reliable option to nail defensive Ghost-types, 2HKOing even the bulkiest of them after Stealth Rock, but Pursuit can be used to trap foes that might attempt to flee from Slaking.Team Options & Additional Comments >>>
Choice Scarf Slaking is designed to use a hit-and-run approach to pick off opposing Pokemon one by one. While the loss of Choice Band's power is disheartening, an Attack stat of 460 is still very threatening, and with an Adamant nature, Slaking reaches a Speed stat of 448, which is enough to outrun numerous common Pokemon; up to Scarfed positive-natured base 85s, which is essentially the entire metagame. These characteristics allow Slaking to become a great revenge killer that can even take a hit or two when needed.
Return is the obligatory STAB move, and it packs an insane amount of power; in fact, it even hits harder than a 2x super effective elemental punch, which is why most of them have been omitted from the set. Earthquake is Slaking's response to Rock- and Steel-types that arrogantly believe they can wall him, while Shadow Claw deals with Ghost-types that are immune to Return. The final slot goes to Ice Punch, which is great for revenge killing Rock Polish Torterra and Bulky Dragon Dance Altaria, both of which are not OHKOed by Return.Team Options & Additional Comments >>>
Slaking has many other options that he can use. Aside from Return, Slaking has four other decent STAB moves that can be used in its place. The first option is Body Slam, which has a cool 30% paralysis rate; however, Slaking is actually quite fast and almost always prefers the extra power that Return offers. The second and third options are Double-Edge and Facade in conjunction with Toxic Orb, and while both are more powerful than Return, they both also greatly undermine Slaking's bulk. The final (and most controversial) option is Giga Impact, and while it is without a doubt Slaking's most powerful attack, it also prevents Slaking from switching out the next turn, which can lead to some disastrous scenarios.
Slack Off and Rest are options to keep Slaking healthy. However, Slaking is better off sticking to attacking moves instead, since the recovery is normally negated when Slaking loafs around. Slaking also has access to Rock Slide, but most of the time the elemental Punches offer greater coverage. Brick Break can be used for a reliable Fighting-type move, but with Earthquake being stronger, and there being no part-Flying or Levitating Steel-types in UU, it's almost always better to use the latter. Night Slash and Shadow Claw are practically interchangeable, so use whichever appeals to you more. Sucker Punch is a powerful priority move, but using it on a Choiced Slaking makes it one of the worst examples of setup bait in the game. A Life Orb set utilizing Sucker Punch is not completely out of the question, though. Taunt can stop Pokemon from setting up on Slaking, and for a huge surprise, Encore can be used to cripple Pokemon that get greedy in doing so. Yawn is also unexpected on Slaking, but many opponents will find themselves switching out from Slaking's attacks anyway.
A wallbreaker set with a Rash nature, an EV spread of 4 Def / 252 SpA / 252 Spe, and a moveset along the lines of Fire Blast / Ice Beam / Thunderbolt / Return has a huge surprise factor, but clever opponents will take advantage of this in any way they can. Other than scoring an occasional KO on the likes of Tangrowth and Donphan, the above set is significantly easier to wall than any of Slaking's other sets, and is therefore less reliable. A Life Orb set is also fine if you feel that the inability to switch attacks is more detrimental than the power boost granted by Choice Band is beneficial. Finally, a Jolly nature can be used on the Choice Band set to outspeed up to positive-natured base 95 Pokemon such as Moltres, Leafeon, and Drapion.
Checks and Counters
While Slaking seems like a divine force that is able to outright destroy just about anything with the right move, he can easily be countered by a number of strategies. The first strategy is to use Protect to stall out Slaking's attacking turn, and then strike him on the turn he loafs around. With this strategy, even physically fragile Pokemon such as Wish + Protect Chansey can easily stall him out. Another strategy is to use Substitute. Similar to Protect-abusing opponents, Slaking cannot win against a Substitute-abusing opponent that is faster than him. A dangerous example of a Pokemon that can abuse this strategy is Mismagius, which can switch in on the majority of Slaking's moveset, set up a Substitute, and then obtain a Calm Mind or Nasty Plot boost before sweeping Slaking's entire team. Substitute Dugtrio is particularly useful as he can trap Slaking with Arena Trap, and take it out, though it can only be brought in on a revenge kill. Finally, Slaking can easily be wasted by using a Pokemon that can take a hit and then use a recovery move to heal off the damage. Slowbro is a perfect example of a Pokemon who can effectively utilize this strategy, taking only a maximum of 66% from a Choice Band-boosted Return, Slaking's strongest attack against it; and by alternating between Slack Off and another one of its moves, it will ultimately triumph over Slaking. Be warned, however, that this last strategy is more prone to being ruined by critical hits than the previous two.