I think my team might need a redo.

[FennekMaster]

So, after playing on the OU tier for a little bit. I have came to the conclusion that my team needs a redo (or at least a major change) and that I need to do something about it. First thing is first if one of my pokemon faints, it is game over for my team and second the pokemon I was building around (Porygon2) just sits there and does nothing. What happens most of the time is that I send out Porygon2 get alot of damage done to it and be unable to use it for the rest of the battle. Sylveon is not much help either as when I need to use it, I am usually against a physical attacker. In other words, my core is useless. Talonflame which is my only sweeper on my team has trouble finding an opportunity to safely switch in. The other half of my team does work decently. Especially, Quagsire and Scizor however, they both fear special attacks and my only specially defensive pokemon is Sylveon. Finally, my team has no win condition so it just ends up being something that just sits there until something good happens. So yeah, my team is not working well. Also, here is what my team looks like:

Porygon2 @ Eviolite
Ability: Trace
EVs: 248 HP / 236 Def / 8 SpA / 16 SpD
Bold Nature
- Thunderbolt
- Ice Beam
- Recover
- Toxic

Sylveon @ Leftovers
Ability: Pixilate
EVs: 248 HP / 8 SpA / 252 SpD
Calm Nature
- Wish
- Heal Bell
- Hyper Voice
- Protect

Talonflame
Ability: Gale Wings
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Swords Dance
- Acrobatics
- Flare Blitz
- Roost

Quagsire @ Leftovers
Ability: Unaware
EVs: 252 HP / 252 Def / 4 SpD
Relaxed Nature
- Scald
- Earthquake
- Recover
- Encore

Scizor @ Scizorite
Ability: Technician
EVs: 248 HP / 8 Atk / 252 Def
Impish Nature
- Defog
- U-turn
- Roost
- Bullet Punch

Celebi @ Leftovers
Ability: Natural Cure
EVs: 252 HP / 156 Def / 84 SpD / 16 Spe
Bold Nature
- Giga Drain
- Recover
- Thunder Wave
- Stealth Rock

Also, no I am not asking for my team to be built for me. I am just asking for ways to fix it.