In terms of ingame use, Scyther/Scizor is probably the best Bug type you can get. Scyther has great Attack and Speed. Scizor has less Speed, but it has even better Attack, better defenses, and the great Bug/Steel typing. Technician is a great ability for them, giving them an incredibly powerful Wing Attack/Aerial Ace that can sweep through the foe.
Scyther (M) @ Expert Belt
Trait: Technician
EVs: 252 Atk / 4 SDef / 252 Spd
Adamant Nature (+Atk, -SAtk)
- Wing Attack/Aerial Ace
- False Swipe
- Rock Smash
- X-Scissor/Bug Bite
Scizor (F) @ Expert Belt
Trait: Swarm/Technician
EVs: 4 HP / 252 Atk / 252 Spd
Adamant Nature (+Atk, -SAtk)
- Iron Head/Bullet Punch
- X-Scissor/Bug Bite
- False Swipe
- Brick Break/Rock Smash
In terms of competitive, Forretress or Scizor depending on what you need it for. Forretress is a better hazard setter and wall. Scizor is a far better sweeper.
Scizor (F) @ Choice Band
Trait: Technician
EVs: 248 HP / 252 Atk / 8 Spd
Adamant Nature (+Atk, -SAtk)
- Bullet Punch
- Pursuit
- Superpower
- U-turn
Forretress (M) @ Leftovers
Trait: Sturdy
EVs: 252 HP / 112 Atk / 144 Def
Relaxed Nature (+Def, -Spd)
- Earthquake
- Gyro Ball
- Rapid Spin
- Toxic Spikes