Not the best set for a Rotom but certainly an interesting one-
Rotom-Heat @ Eject Pack
Ability: Levitate
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Thunderbolt / Discharge
- Hex
- Overheat
- Thunder Wave / Nasty Plot / Will-O-Wisp
Use Thunderbolt with Thunder Wave / Will-O-Wisp and Discharge with Nasty Plot
Eject Pack switches the Pokemon out if it has a stat lowered, so you use Overheat then Eject Pack switches Rotom out, the you use Volt Switch or U-turn to switch Rotom back in getting rid of your stat drops while constantly doing damage to the opposing Pokemon.
Other than that you use Thunder Wave to paralyze or Will-O-Wisp to burn and use 130 power Hex with Thunderbolt as main Electric-type STAB. Or use Discharge to paralyze with Nasty Plot to raise the SpA. Depends if you want a higher chance to paralyze or ability to boost stats. Most people would prefer Discharge and Nasty Plot.
If you don't want to utilize the status + Hex strategy at all I would suggest :
Rotom-Heat @ Eject Pack
Ability: Levitate
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Thunderbolt / Thunder
- Overheat
- Volt Switch / Shadow Ball
- Nasty Plot
Thunder is an option if you don't care about low accuracy.