Maybe I should just make a Monotype flying team since Flying OU pokémon shouldn't be left out.
@Andrew: I agree. Competitive battle preparation is tedious and sometimes intimidating! However, your hard work pays off so much!
Here are some guidelines
First, know all of the terms of Pokémon in competitive battling. These can include
Offensive:
-Physical/Special Attacker (offensive Pokémon with either all physical moves or special moves, mainly requires Pokémon high in Speed as well)
-Mixed Attacker (has good Attack and Sp.Attack along with a great mixed movepool, Speed also quite necessary)
-(Physical/Special) Tank (high in Attack/Sp.Attack and/or Defense/Sp.Defense with a good offensive movepool, Speed is necessary, but working on defenses is still priority)
-Bulky Attacker (similar high offense and defense, can provide more hits than most attackers)
-Glass Cannon/All-Out Attacker (attacks other team with no intention to play safe. Low defenses, high offense, good-high speed, and decent-good HP)
-SubPunch (refers to Pokémon with Substitute and Focus Punch)
Supportive-Defensive:
-SubSeed (refers to Pokémon with Substitute and Leech Seed)
-Wall (high defensive qualities, HP training is necessary, may not have too many attacks but makes up for it with keeping the opponent at bay)
-DualScreens (refers to Walls that raise the team's Defense and Sp.Defense with Reflect and Light Screen, attackers can land more hits because the whole team's defenses were raised)
-Stalls (high HP & Defense/Sp.Defense, uses non-attacking moves to keep the battle from progressing (hence stall), induces sleep or poisons opponent while staying protected by certain moves)
-StallBreaker (uses Taunt to keep Stallers from holding up the battle, Stall Pokémon with four non-attacking moves will result in Struggle, can attack and faint a Stall) (stallbreakers are really more supportive than offensive)
-Passers (Pokémon who use Baton Pass after raising their own stats and pass the increase to the next Pokémon)
-Support (provides good support to other members by helping them recover HP or induce status conditions that may activate the other Pokémon's ability)
These are general battle roles that can be used in really effective ways. DualScreen Pokémon can give good support to Tanks and Attackers in general.
If you need to find Pokémon that can give you Effort Values, you can check the main site in the Game Mechanics section.