Deal or No Deal
The title above shows the main idea for my team: my pokemons are built mainly to counter the pokemons that are often used to switch in to hit it. Therefore, with a correct prediction, my pokemon will do a huge damage on the switched pokemon.
For example, many of the players switch in Magnezone to trap and kill Jirachi (as normal Jirachi set are not every effective to hit Magnezone). Scizor and Forretress are also considered as safe to suffer physical Jirachi's attacks. Therefore, with Fire Punch, my Jirachi can make a big surprise, take a lot of HP from the enemy (if not OKHO), and make my rival think twice ("Deal or No Deal") before switching such pokemon in next time.
My team is also designed to counter most popular power-boosted-pokemons nowadays, such as Salamance/Gyarados after 1 Dragon Dance, Scizor/Lucario after 1 or 2 Sword Dance, Suicuine/Jirachi after 1 or 2 Calm Mind, etc.
After all, it is my team:
Jirachi - lead
Blissey - special wall
Donphan - physical wall
Heatran - versatile scarftran
Starmie - special sweeper
Salamance - physical sweeper
The versatile leader

Jirachi @ Choice Scarf
Ability: Serene Grace
EVs: 80 HP / 252 Atk / 176 Speed
Nature: Jolly
Move:
Iron Head
Stealth Rock
Fire Punch
Trick
I call it "versatile leader", as it can be used for multi-functions:
- Set hazard entry: No lead without Scarf can be faster than my Jirachi, and of course, if the enemy team's lead holding Scarf, it will not waste a turn to Taunt my Jirachi and switch out. Therefore, when starting the battle, I can ensure the Stealth Rock is always set. In some lucky cases, if the enemy team's lead is Azelf or Aerodactyl, there is a high chance that it will use Taunt. Of course, as my Jirachi is faster, my rival will waste 1 turn.
- Disable one wall with Scarf: Blissey, Snorlax Curse and Suicuine Calm mind are really annoying, but luckily all of them are useless if being stuck into a Scarf. Both Snorlax and Suicuine are quite ready to tank and use Curse/Calm mind followed by Rest when realizing that my Jirachi has Fire Punch, instead of Thunder Punch. Therefore, being tricked to Scarf, they will be stuck in Curse or Calm mind forever, and even if they are switched out, Blissey/Snorlax/Suicuine will become useless after that.
- Remove Jirachi's counter: Scizor, Lucario, Forrestress, and Magnezone are considered as safe choices to switch in to suffer Jirachi's attack. All of them are weak to Fire. After switch in, normally Scizor and Lucario will use Sword Dance, Forrestress rapid spins or set hazard entries, and Magnezone traps and try to kill Jirachi. Faster than all of them, Jirachi's Fire punch damages them more than 50% HP, and combined a little with SR, those four pokemons will barely die after that (or OKHO for Scizor's case).
- Hit and tank: with Serene Grace, Iron Head has 60% of causing enemy to be flinched. With 252 EVs for Atk and STAB, this move is really worth to use. Different from a slow Togekiss, there are not many pokemon can outspeed Jolly Jirachi 176 EVs Speed (even without Scarf), and so, Iron head would be quite useful.
The prudent cleric

Blissey @ Leftovers
Ability: Natural Cure
EVs: 150 HP / 252 Def / 76 Spc Atk / 26 Spc Def / 6 Speed
Nature: Bold
Move:
Aromatherapy
Softboiled
Shadow Ball
Toxic
The main jobs for my Blissey are to be a special wall, heal her teammates' statuses and poison enemy pokemons.
- A full HP Blissey are safe to be switched in almost OU special attack pokemons, except Gengar/Alakazam max Spc. Atk Choice Spec Focus Blast (which are very, very rare nowadays). As no player wants to waste one special atk pokemon, they will switch another pokemon in, so my Blissey can have a turn to heal her teammates with Aromatherapy, recover with Softboiled, or badly poison the next pokemon with Toxic.
- Normal Blissey has Seismic Toss, so Gengar can be switched in to hit her with Focus Blast. After a SR, Blissey's Shadow Ball will 2KO Gengar. For other Ghost Pokemon, Shadow Ball also work very well. Moreover, interestingly, Shadow Ball is enough to break Breloom's Subtitute, i.e., prevent its Focus Punch.
- 150 HP and 252 Def help Blissey takes physical hit, and once the enemy pokemon is badly poisoned, everything Blissey has to do is to stand and keep using Softboiled until the enemy pokemon is poisoned to death. However, this strategy is not applicable to very offensive pokemons (for example, 252 EV Atk Salamence/Gyarados), or fighting pokemons (Machamp, Infernape...). Such cases would be the time to switch Donphan or Salamence in.
The dragon killer

Donphan @ Leftovers
Ability: Sturdy
EVs: 252 HP / 112 Atk / 146 Def
Nature: Adamant
Move:
Rapid Spin
Earthquake
Assurance
Ice Shard
My Donphan is used as a physical wall, a rapid spinner, a dragon killer, and Steel-type sweeper.
- With 252 EVs HP and 146 EVs Def, Donphan is a reliable physical wall, who can suffer hit and pay back the enemy with its high attack after that.
- Its priority move Ice Shard is 4x effective to the most common dragon: Salamence, Dragonite and Flygon. After switch in, it will use Ice Shard, damage a huge HP from those dragons, suffer one attack (even Salamence's or Dragonite's Outrage after one or two Dragon Dance), then use Ice Shard again to finish those dragons.
- As a rapin spinner, if my rival has a ghost pokemon in his team, there is a high chance that he will switch it in to prevent my Donphan from spinning. It is the time Assurance to work. With the power quadrupled thanks to SR and effectiveness, the power of this move will be 200. If it cannot KO, Donphan's Ice Shard will do this task next turn, so nothing can prevent my spinner from spinning anymore.
- With high attack and STAB, Earthquake it really worth to used. It can OKO Heatran, Infernape, and even Jirachi after SR. It also help Donphan to tank and hit Metagross.
The sacrificer

Heatran @ Choice Scarf
Ability: Flash Fire
EVs: 6 Atk / 252 Spc Atk / 252 Speed
Nature: Naive
Move:
Flamethrower
Earth Power
Hidden Power Ice
Explosion
Heatran's Flamethrower is powerful, and it can KO a lot of pokemons after Flash Fire and SR. Earthpower is useful to kill Infernape and other slower Heatran (what are very popular, as my Heatran's speed is maximum). Hidden Power Ice can kill common Dragons, who are trying to remove Heatran by Earthquake. With Scarf, my Heatran can easily remove Scizor or Lucario, even if they have boosted Sword Dance once or twice.
With maximum speed, my Heatran can out-speed ALL Gyrados and Kingdra after 1 Dragon Dance, unless they are Jolly and have 252 EVs for Speed. After 1 Dragon Dance, Gyarados/Kingdra will surely use Waterfall to hit Heatran and my rival will be quite surprising when seeing his pokemon faints after the turn due to my Heatran's explosion.
The shining star

Starmie @ Life Orb
Ability: Natural Cure
EVs: 6 HP / 252 Spc Atk / 252 Speed
Nature: Timid
Move:
Surf
Psychic
Ice Beam
Thunderbolt
Personally, I think that Starmie is one of the most useful special sweeper.
- The base speed of 115 and maximum EVs/Nature for speed help it out-speed all OU non-scarf pokemons, except Ninjiask, Jolteon, Aerodactly, and Wealive. No one uses Ninjiask or Aerodactly to counter Starmie, so only Jolteon and Wealive left. Jolteon is easily lured by my Blissey, and Wealive can do nothing when I switch in my Heatran.
- Surf is its most powerful attack, with 252 EVs for Special Attack, Life Orb and STAB, it can do quite a little damage on everything that does not resist it. It is also used to KO Infernape, Heatran, Glisor, Mamoswine, Hippowdon... (especially after SR), and 2KO many other pokemons (Scizor, Tyranitar, Rotom (all forms), Magnezone...).
- Psychic also receives STAB, what is to KO Machamp, Hitmantop and Gengar (after SR). It is also the most powerful attack to hit Kingdra and Tentacruel (2KO).
- Thunderbolt is used to to kill Gyrados. Starmie can suffer Gyarados' Earthquake or Stone Edge or Waterfall even after 1 Dragon Dance, and then finish it with thunderbolt.
- Icebeam is used to KO common dragon pokemons (except Kingdra).
The rise of power

Salamence @ Life Orb
Ability: Intimidate
EVs: 232 Atk / 26 Spc Atk / 252 Speed
Nature: Naive
Move:
Outrage
Draco Meteor
Earthquake
Fire Blast
My Salamence is the most offensive pokemon in my team, and it possesses most powerful attacks. Its all functions are attack, attack and attack.
The speed of Salamence is maximum so that it has a high chance to out-speed other 100 base speed pokemons, who are very common in OU nowadays.
With Life Orb and 232 EVs for Atk, Outrage do a huge damage on all non-steel pokemons. For steel pokemons, it is time to use Earthquake and Fire Blast. Earthquake has 100% accuracy and it can take full advantage of Salamence's high attack, but it does not affect Skarmony and do little damage on highly physical defensive steel pokemons. In such cases, Fire Blast becomes useful. Earthquake also help Salamance to face to Heatran, in which case both Outrage, Draco Meteor and Fire Blast is useless.
My Salamence learns Draco Meteor, instead of Dragon Dance, because I found it more useful. When a Salamence is switched in to face to a vulnerable pokemon (for example, Skarmony or non-scarf Heatran); most of players will use one free turn (in which the enemy takes to switch other pokemon in to counter Salamence) to use Dragon Dance. However, as it is so common, almost everyone will switch pokemon that is not afraid DD Salamence, for example, a pokemon with Ice Shard. In such cases, the player will have to withdraw Salamence, and the Dragon Dance turn is wasted. Therefore, using Draco Meteor, my Salamence can take a lot of HP from the switched pokemon (or even OKHO it), and then run next turn to prevent from being threatened by Ice Shard.
Conclusion
After all, you may ask why 3 pokemons (Heatran, Salamence and Jirachi) must have Fire type moves? Similarly, 3 pokemons (Heatran, Donphan and Starmie) has Ice type moves, and 3 pokemons (Heatran, Donphan and Salamence) has Earth type moves. Are they superabundant and excessive?
I chose them purposely, because they are super effective to Dragon and Steel pokemons, who are very popular in OU nowadays. By having more than 1 pokemon knowing this type of move, I can ensure that even a pokemon faints, there are someone can take its part. Also, despite the face that sharing same types, the moves are also have slightly differences, as well as the pokemon having the moves are totally distinctive what should be used in different cases.
I have tried my best to build and organize my team, however, in some cases, I cannot do anything other than ragequitting or losing. One example is to face some sort of a baton pass team, as all of my pokemons do not have Taunt or Encore or a powerful priority move. To everyone who has read my thread, please help me to rate and optimize it. Thank you very much.