Linoone possesses a holy trinity of sweeping power: Belly Drum, STAB Extreme Speed, and Gluttony. These three elements combine to form the ultimate one-turn setup. After a Belly Drum, Linoone's shabby Attack stat of 262 skyrockets to an amazing 1048, ready for immediate sweepage. At the same time, Gluttony activates its Salac Berry, sending its Speed stat from 270 (136 EVs) to 405, outspeeding everything up to neutral-natured Pokemon with a Choice Scarf and base 85 Speed. Linoone can then proceed to sweep with Extreme Speed, a STAB 80 Base Power priority move that essentially ensures that the flipped-out polecat will almost never be struck before it can hit, and likely KO its opponent. Seed Bomb is the second attack in Linoone's sweeping arsenal, KOing many of the Rock-types that resist Extreme Speed, as well as doing a hefty number on bulky Water- and Ground-types. Assuming maximum defensive investment, Slowbro, Milotic, Claydol, Omastar, Quagsire, Cloyster, Rhyperior, Sandslash, Relicanth, and Gastrodon will all survive a +6 Extreme Speed, but will all fall to +6 Seed Bomb after Stealth Rock. Despite its large movepool, Linoone has very few usable offensive options. After Extreme Speed and Seed Bomb, those options boil down to the two in the last moveslot. Shadow Claw is for Ghost-types, and will OHKO any Ghost-type in UU, bar Spiritomb and Sableye, without fail (Stealth Rock is needed for an OHKO on Dusclops). Return, however, may prove more useful in the long run.
Return may seem like redundant coverage with Extreme Speed, allowing you to be walled by many more opponents, but consider the following; there are five Ghost-types in UU that +6 Shadow Claw can OHKO but +6 Seed Bomb cannot. These are Drifblim, Dusclops, Mismagius, max Defense Rotom, and Shedinja. Drifblim and Dusclops, while not unseen, are rare. Drifblim is often used as a lead in UU and will probably have Substituted down to 25% of its health (easily KO range) by the time Linoone is on the scene. Bold Rotom is also a rare sight - offensive variations are much more common and are all KOed by Seed Bomb. Shedinja is the rarest of all, and though lacking Shadow Claw will leave you completely walled by Shedinja, even with Shadow Claw most will either kill you after Focus Sash activates, or with a Sucker Punch. This is, of course, assuming there is no Stealth Rock on the field, which renders Shedinja useless anyway. Return, meanwhile, rivaling in power practically any Explosion found in UU, will ensure a few KOs that Extreme Speed cannot. Max Defense Weezing, Nidoqueen, Torterra, Uxie, and Drapion are all OHKOed by +6 Return after Stealth Rock damage, while Extreme Speed (or Shadow Claw vs. Uxie) will fail to KO in each case by a small margin. Return also has a 65% chance of 2HKOing a 252 HP / 4 Def neutral-natured Registeel holding Leftovers and taking Stealth Rock damage. Finally, after possibly taking an Intimidate or two, the added power of Return will be welcome.
Steel-type Pokemon are the one thing Linoone absolutely cannot sweep through, as they resist Linoone's STAB attacks as well as Seed Bomb. Two attack options - Dig and Rock Smash - were available in the past as Linoone's only super effective attacks against the Steel-types, but neither is recommended over the listed attacks. Dig is nearly useless; not only is it easy to avoid and fails to OHKO Steelix, but Steelix and Registeel usually carry Earthquake, which will hit you underground. Rock Smash is generally a waste of a moveslot, considering a 2x super effective Rock Smash has only 80 Base Power, and a resisted STAB Return has 76.5 Base Power. Seed Bomb hits Steelix with 80 Base Power as well. The only Steel-types that Rock Smash is able to hit for decent damage are the three Rock / Steel-types (Bastiodon, Probopass, and Aggron), which, except for Aggron, are rarely seen.
It therefore falls upon Linoone's teammates to remove its counters if Linoone hopes to sweep. Before firing off a Belly Drum, scouting for opposing Steelix, Registeel, and Spiritomb is wise. Shuckle, Cradily, and Armaldo are not as common nor as perfect of counters, but can all pose problems for Linoone as well. These sweep-stopping Pokemon should be eliminated, or else brought within KO range, before Linoone Belly Drums. Assuming Stealth Rock is in play, Linoone will always KO these counters if they are taken down to a certain hit point percentage first:
+6 Seed Bomb vs. 252 HP / 0 Def Impish Steelix - 35.6% - 41.8%
+6 Return vs. 252 HP / 252 Def Impish Registeel - 36% - 42.6%
+6 Return vs. 252 HP / 0 Def Careful Registeel - 47% - 55.2%
+6 Seed Bomb vs. 252 HP / 252 Def Bold Spiritomb - 57.2% - 67.4%
+6 Seed Bomb vs. 252 HP / 240 Def Careful Cradily - 55.1% - 64.9%
+6 Seed Bomb vs. 244 HP / 252 Def Impish Armaldo - 52% - 61.4%
+6 Seed Bomb vs. 0 HP / 4 Def Jolly Aggron - 54.1% - 63.3%
Keeping these Pokemon in mind, a team packing Linoone would do well to carry Pokemon who can handle Linoone's counters. Powerful wallbreakers such as mixed Blaziken, Swords Dance Pinsir, and Choice Specs Typhlosion can soften these counters enough for Linoone to sweep, if not KOing them outright. Also, as with any setup sweeper, lures and trappers make Linoone's life much easier. Mismagius, Scyther, and Swellow are all terrific lures that can coax your opponent's Linoone counter early. Dugtrio and Magneton are fairly efficient at eliminating the Steel-types that give Linoone nightmares, especially when paired with lures. Dual Screen users such as Uxie and Mesprit can help soften blows that Linoone might take whilst setting up, thus making its job easier.
If you are worried about outspeeding certain Choice Scarf Pokemon (such as Venusaur and Rotom), a Jolly nature is optional. However, you will miss out on many crucial OHKOs if you do this, namely Slowbro, who is always OHKOed if Stealth Rock is in play, with a high chance of OHKOing without Stealth Rock. A Jolly nature will cause you to only OHKO with Stealth Rock set up. A different EV spread of 36 HP / 252 Atk / 4 Def / 216 Spe with a Jolly nature can be used to guarantee the ability to outspeed certain other Pokemon; however, there is a noticeable lack in power. Finally, Memento Gastrodon is one of the easiest ways to guarantee a successful set up. Gastrodon has access to three extremely helpful support moves: Block, Memento, and Yawn.