Welp, FLCL's set is almost identical to the one I was gonna post.
Let's try something else! :D
Scolipede @ Life Orb/Expert Belt
Trait: Swarm
EVs: 252 Atk/4 Def/252 Speed
Jolly Nature
- Swords Dance
- Baton Pass
- Megahorn
- Aqua Tail
Even though this set is not that much different from FLCL's set, it definitely still has its own merits. Water/Bug is actually really good coverage in NU, leaving its main counters to Altaria, Misdreavus, Frillish, and Water/Flying type Pokemon. Of those, mainly only Altaria and Misdreavus are truly an issue (due to Frillish's rarity in NU and Water/Flying types' general low quality). Since Earthquake isn't going to hit any of these Pokemon at all (bar Frillish who is hit almost as hard with Megahorn), Baton Pass doesn't really cost it much in terms of coverage. Baton Pass is viable for a few reasons: you can obviously pass off Swords Dance boosts against checks/counters or just before dying, but more importantly, this set can also serve as a scout, luring in Scolipede's checks and eliminating them so that you may sweep with it later on. That said, you don't even have to partner this set with good recipients of the boosts (though it is good to have something that would appreciate an SD boost).
Here are some relevant calcs:
252Atk +2 Scolipede (Neutral) Aqua Tail vs 252HP/0Def Golurk (Neutral): 96% - 113% (368 - 434 HP). Guaranteed 2HKO. 78% chance to OHKO.
Without a boosting item, you can miss out on the OHKO against Golurk. Though it's not likely, it very well could be gamebreaking.
252Atk +2 Scolipede (Neutral) Aqua Tail vs 252HP/0Def Regirock (Neutral): 45% - 53% (166 - 196 HP). Guaranteed 3HKO. 12% chance to 2HKO.
Same thing goes with Regirock; without a boosting item (especially if the opponent's Regirock runs Leftovers), chances are you won't be able to 2HKO with Aqua Tail. Either Expert Belt or Life Orb remedies this and guarantees the 2HKO. Meanwhile, even Adamant max attack Regirock can miss out on the OHKO with Rock Slide if you're still at 100%. Specially Defensive Regirock never OHKOs from full.
Basically, this set is less of a dedicated Baton Passer and more of a scout or set-up sweeper. The lack of EQ is not really that big of a deal when considering the set's checks and counters. Good partners to this are Pokemon who can keep up the momentum
with access to Volt Switch such as the Rotom formes, Electrode, and Zebstrika who can also destroy the Water/Other types that cause issues for this set, as well as Swellow who can absorb a Burn and then immediately threaten Misdreavus or U-Turn out.