Well, I've decided to start getting a team for competitive battling.
First off, I started with Jirachi. I knew that I would need Wish supprt for the team in mind, and I just happened to have an unclaimed Jirachi on my SS file.
A lead was needed. Preferably with Stealth Rock, so I chose Swampert. It also fulfilled the role of Bulky Water.
On the offensive side of the team, I started with a revenge killer; Scizor.
I threw in Tyranitar, since the other three Pokémon were all immune to Sandstorm and that it synergized well with Scizor.
Toxic Spikes was needed, so I instantly went to specially defensive Forretress. However, it shared Scizor's 4x Fire weakness, so I went to Tentacruel. Looking back at my team, Swampert seemed to be a threat, so I picked the only other Toxic Spiker in the OU metagame: Roserade.
And finally, I needed a spinblocker. I settled on Rotom-H for its synergy with Jirachi, but that can change to any other Rotom form. I placed Roserade as the lead after realizing that my custom build wasn't exactly working, and switched to Toxic Spikes Lead.
I switched Rotom-H out for Gengar due to Gengar's access to Pain Split and synergy with Toxic Spikes. Which means Tyranitar's Sand Stream won't be helping, so I replaced it with Flygon.
A closer look reveals...
Roserade @Focus Sash
Timid Nature, Natural Cure
4 HP/252 SpA/252 Spe
-Grass Knot
-Toxic Spikes
-Sleep Powder
-Aromatherapy/HP Ice(In Shoddy)
I know that a lead shouldn't have Aromatherapy, but it's there for supportive uses if Roserade actually survives (which, I might add, is unlikely, but I don't feel like getting a Hidden Power Ice Roserade). A basic Toxic Spikes lead, it can cripple the slower leads with Sleep Powder and proceed to set up Toxic Spikes. Grass Knot can destroy Tyranitar leads after setting up, as well as Swampert leads.
Swampert @Leftovers
Relaxed Nature, Torrent
240 HP/216 Def/52 SpD
-Stealth Rock
-Earthquake
-Ice Beam
-Roar
MixPert Tank Swampert can set up Stealth Rock rather reliably when it's sent out. Earthquake is there for STAB, while Ice Beam takes care of Flying types and Levitators that are immune to EQ. Finally, Roar can be used as a phazing move while forcing the opponent to switch and take damage from Stealth Rocks.
Gengar @Life Orb
Timid, Levitate
252 SpA/252 Spe/4 HP
-Substitute
-Shadow Ball
-Focus Blast
-Pain Split
This Gengar can stall the opponent while it suffers from Toxic Spikes. With Substitute, it can actually survive more than a single turn. Shadow Ball is there for STAB and Focus Blast takes care of Tyranitars. Sub+Focus Blast takes care of Scarf variants of Tyranitar. Pain Split offers damage and healing in one turn.
Scizor @Choice Scarf
Jolly Nature, Technician
12 HP/252 Atk/244 Spe
-Bullet Punch
-Pursuit
-Superpower
-U-Turn
Revenge killer and scout, all in one place! Bullet Punch is for STAB and priority, and will kill off many weakened Pokémon that are weak to it. It can also Pursuit a Ghost or Psychic-type, cutting off its escape. Superpower is for Blissey and Snorlax, while U-Turn is its main scouting move.
Jirachi @Leftovers
Bold Nature, Serene Grace
252 HP/224 Def/32 Spe
-Wish
-Calm Mind
-Thunderbolt
-Psychic
Wish support with Calm Mind is probably best for this role. Wish is the crux of this build (and Jirachi's signature move), while Calm Mind provides a boost in offense and defense. Psychic for STAB, Thunderbolt for type coverage. Why Psychic? It's more powerful than Flash Cannon.
Flygon @Choice Scarf
Jolly Nature, Levitate
252 Atk/4 SpD/252 Spe
-Earthquake
-Outrage
-U-Turn
-Fire Blast
A scout/revenge killer Flygon works well with Scizor, according to the Smogon page. Earthquake is very powerful, with STAB boosting its base power from 100 to 150. Outrage is even more powerful, however Flygon would be prone to revenge killing if it gets locked into it. U-Turn for scouting purposes, and Fire Blast to deal with Steels.
First off, I started with Jirachi. I knew that I would need Wish supprt for the team in mind, and I just happened to have an unclaimed Jirachi on my SS file.
A lead was needed. Preferably with Stealth Rock, so I chose Swampert. It also fulfilled the role of Bulky Water.
On the offensive side of the team, I started with a revenge killer; Scizor.
I threw in Tyranitar, since the other three Pokémon were all immune to Sandstorm and that it synergized well with Scizor.
Toxic Spikes was needed, so I instantly went to specially defensive Forretress. However, it shared Scizor's 4x Fire weakness, so I went to Tentacruel. Looking back at my team, Swampert seemed to be a threat, so I picked the only other Toxic Spiker in the OU metagame: Roserade.
And finally, I needed a spinblocker. I settled on Rotom-H for its synergy with Jirachi, but that can change to any other Rotom form. I placed Roserade as the lead after realizing that my custom build wasn't exactly working, and switched to Toxic Spikes Lead.
I switched Rotom-H out for Gengar due to Gengar's access to Pain Split and synergy with Toxic Spikes. Which means Tyranitar's Sand Stream won't be helping, so I replaced it with Flygon.
A closer look reveals...
Roserade @Focus Sash
Timid Nature, Natural Cure
4 HP/252 SpA/252 Spe
-Grass Knot
-Toxic Spikes
-Sleep Powder
-Aromatherapy/HP Ice(In Shoddy)
I know that a lead shouldn't have Aromatherapy, but it's there for supportive uses if Roserade actually survives (which, I might add, is unlikely, but I don't feel like getting a Hidden Power Ice Roserade). A basic Toxic Spikes lead, it can cripple the slower leads with Sleep Powder and proceed to set up Toxic Spikes. Grass Knot can destroy Tyranitar leads after setting up, as well as Swampert leads.
Swampert @Leftovers
Relaxed Nature, Torrent
240 HP/216 Def/52 SpD
-Stealth Rock
-Earthquake
-Ice Beam
-Roar
MixPert Tank Swampert can set up Stealth Rock rather reliably when it's sent out. Earthquake is there for STAB, while Ice Beam takes care of Flying types and Levitators that are immune to EQ. Finally, Roar can be used as a phazing move while forcing the opponent to switch and take damage from Stealth Rocks.
Gengar @Life Orb
Timid, Levitate
252 SpA/252 Spe/4 HP
-Substitute
-Shadow Ball
-Focus Blast
-Pain Split
This Gengar can stall the opponent while it suffers from Toxic Spikes. With Substitute, it can actually survive more than a single turn. Shadow Ball is there for STAB and Focus Blast takes care of Tyranitars. Sub+Focus Blast takes care of Scarf variants of Tyranitar. Pain Split offers damage and healing in one turn.
Scizor @Choice Scarf
Jolly Nature, Technician
12 HP/252 Atk/244 Spe
-Bullet Punch
-Pursuit
-Superpower
-U-Turn
Revenge killer and scout, all in one place! Bullet Punch is for STAB and priority, and will kill off many weakened Pokémon that are weak to it. It can also Pursuit a Ghost or Psychic-type, cutting off its escape. Superpower is for Blissey and Snorlax, while U-Turn is its main scouting move.
Jirachi @Leftovers
Bold Nature, Serene Grace
252 HP/224 Def/32 Spe
-Wish
-Calm Mind
-Thunderbolt
-Psychic
Wish support with Calm Mind is probably best for this role. Wish is the crux of this build (and Jirachi's signature move), while Calm Mind provides a boost in offense and defense. Psychic for STAB, Thunderbolt for type coverage. Why Psychic? It's more powerful than Flash Cannon.
Flygon @Choice Scarf
Jolly Nature, Levitate
252 Atk/4 SpD/252 Spe
-Earthquake
-Outrage
-U-Turn
-Fire Blast
A scout/revenge killer Flygon works well with Scizor, according to the Smogon page. Earthquake is very powerful, with STAB boosting its base power from 100 to 150. Outrage is even more powerful, however Flygon would be prone to revenge killing if it gets locked into it. U-Turn for scouting purposes, and Fire Blast to deal with Steels.