Let's talk about the Rotom Formes! :D
Rotom-Mow @ Sitrus Berry
Trait: Levitate
EVs: 240 HP / 252 SAtk / 16 SDef
Modest Nature
- Seed Flare / Giga Drain
- Thunderbolt
- Spore
- Protect / Leech Seed
Bulky Rotom-Mow works similar to Rotom-W in terms of being a Rain Check, except instead of using it to boost its STAB like Wash, it has 2 STABS that destroy Water-types and can use Rain to nullify its Fire weakness. Seed Flare is the strongest STAB that Rotom-Mow can use, and has a nasty side effect. Giga Drain can be used instead for more HP, but the power difference is huge. Thunderbolt is the electric STAB that helps destroy some Water-types and Flying-types that think they can resists its Grass STABs. Spore is really useful, and what really sets it apart from the other Rotom Forms. Protect is staple, but Leech Seed can be used for more recovery.
Rotom-Mow @ Choice Scarf / Choice Specs
Trait: Levitate
EVs: 252 Spd / 252 SAtk / 4 SDef (Scarf) or 240 HP / 252 SpA / 16 SpD (Specs)
Timid Nature / Modest Nature
- Seed Flare
- Thunderbolt / Thunder
- Hidden Power [Ice] / Hidden Power [Fire] / Trick / Destiny Bond
- Volt Switch / Trick / Destiny Bond
This set (more like 2 sets - Scard and Specs play very differenly) really lets Rotom Mow through Rain and Sand Teams. Seed Flare is chosen as main STAB as it wrecks Water-, Rock-, and Ground-types, and can lower SpDef by 2 stages. Thunderbolt is secondary STAB and is more reliable than Seed Flare. Thunder can be used if you're in a Rain Team, but TBolt is more desirable. HP Ice lets you hit Dragon- and Grass-types that resist both your STABs. HP Fire is also an option to wreck Ferrothorn and other Steels that resists your STAB Combo, along side the Grass-types. Volt Switch gives you momentum, so its pretty nifty. Trick is an option to cripple walls when you are low. Destiny Bond is a neat move, especially on the Scarf Set, when you're about to die, as it lets you bring one with you. It can get DBond from Normal Rotom, as it is a Ghost-type.
Rotom-Fan @ Sitrus Berry
Trait: Levitate
EVs: 240 HP / 252 SAtk / 16 SDef
Modest Nature
- Aeroblast / Air Slash / Hurricane
- Thunderbolt / Thunder
- Will-O-Wisp
- Tailwind / Protect / Destiny Bond
Rotom-Fan has to compete directly with Zapdos and both Thundurus Forms. Fortunantely, Rotom-Fan has something over the two - Will-o-Wisp. This lets Rotom-Fan to be much more bulky than it really is. Aeroblast and TBolt are strong STABs, although Air Slash can be used if you want some flinch fun. Hurricane and Thunder are an option if you use this in a Rain Team, although those moves might be better on a Scarf/Specs set. Will-O-Wisp is what makes Rotom-Fan unique, as it lets it burn pokemon unlike Thundy and Zapdos. Tailwind gives your team a speed boost, while Protect is a staple. DBond is an option here as well, as that is also a thing that Thundy and Zapdos don't have.
Rotom-Fan @ Choice Scarf / Choice Specs
Trait: Levitate
EVs: 252 Spd / 252 SAtk / 4 SDef (Scarf) or 240 HP / 252 SpA / 16 SpD (Specs)
Timid Nature
- Hurricane / Aeroblast / Air Slash
- Thunder / Thunderbolt
- Destiny Bond / Trick
- Volt Switch / Air Slash
This set competes directly with Thundy and Zapdos, but it does have some unique features. This set is meant to be used in a Rain Team, which is why Hurricane ad Thunder are the main STABs here. TBolt and Aeroblast are options for non-Rain Teams. Air Slash can be annoying on a scarf set. DBond and Trick are things that make Rotom-F different from Zapdos and Thundy. DBond lets Rotom-Fan make a last kill before dying, while Trick cripples walls. Volt Switch is momentum. Again, Air Slash is annoying on a Scarf Set, so that's an option.
Too lazy to do Rotom-Heat an Rotom-Wash, but all they really get is a 30% chance to Burn and some neat spread moves. Rotom-Heat does get some strong STABs though, like Blue Flare or Fiery Dance (Scarf). Rotom-Frost could be cool in Hail teams, but I don't see it doing much else. Glaciate is a thing I guess.