Turkey Dinner (Rotom-H) @ White Herb/ Leftovers/ Choice Scarf
EVs: 252 SAtk / 4 SDef / (252 Spd or 252HP)
Timid Nature (+Spd, -Atk)
- Volt Switch
This poke resist every single one of those moves on the standard Choice Scarf Genesect (Fire, Electric, Ice, & Bug). It is also immune to HP [Ground]. If it just so happened to be raining, it still OHKO Genesect with Overheat and will be faster with a Choice Scarf since most Rain Genesect run Life Orb.
Since Rotom-H has equal defenses, put the last 4 EVs to SpDef so Genesect can't get any boosts on a switch (better safe than sorry). Also gives more switches on SR, so it's a win-win.
Just for fun:
0SpAtk Rotom (-SAtk) Overheat vs 252HP/252SpDef Leftovers Genesect (+SpDef): 107% - 126% (372 - 436 HP). Guaranteed OHKO.
So even an uninvested negative natured Overheat will OHKO a Max HP/ Sp.Def Genesect.
Note: This calculation was done under normal weather. Don't get cocky when it is raining.
Magnezone @ Leftovers
Trait: Magnet Pull
EVs: 252 HP / 164 SAtk / 92 SDef
Modest Nature (+SAtk, -Atk)
- Hidden Power [Fire]
- Flash Cannon
- Tri Attack
This is if you want to trap Genesect.
This poke resist BoltBeam & U-Turn. Only problem is Flamethrower. If you can switch in on BoltBeam, Awesome. but in the event that you need to go up against Flamethrower, do not fear. This EV spread is meant to take a +1 Flamethrower. 2HKO. But you only need one to singe that Kabutops imposter. 164 SpAtk EVs is enough to OHKO with HP [Fire].
252SpAtk +1 Genesect (Neutral) Flamethrower vs 252HP/92SpDef Leftovers Sturdy Magnezone (Neutral): 84% - 99% (290 - 342 HP). Guaranteed 2HKO.
Hidden Power [Fire} is 2HKO in Rain. However, on Magnezone:
Flamethrower in Rain is 4HKO
+1 Flamethrower in Rain is 3HKO