Suggestions for first OU team

[Eatmyflamethrower]

Hi, I'm very new to competitive battling; I played a few matches three years ago but I don't really remember much. I'm trying to put together a decent team and I have the following pokemon already plus money to potentially breed one more (I really prefer 1st and 2nd generation pokemon due to nostalgia lol). If anyone has ideas about the best team I could put together from these pokemon and possibly one other one I'd really appreciate it! Suggestions for changes to movesets/items/abilities would also be welcome.

 

Gyarados (M) @ Leftovers
Ability: Intimidate
EVs: 6 HP / 252 Atk / 252 Spe
Adamant Nature
- Dragon Dance
- Waterfall
- Ice Fang
- Earthquake

 

Gengar (M) @ Black Sludge
Ability: Cursed Body
EVs: 6 HP / 252 SpA / 252 Spe
Timid Nature
- Focus Blast
- Hidden Power Fire
- Nasty Plot
- Shadow Ball

 

Skarmory (M) @ Rocky Helmet
Ability: Sturdy
EVs: 252 HP / 6 Atk / 252 Def
Impish Nature
- Roost
- Stealth Rock
- Roar
- Brave Bird

 

Blissey (F) @ Leftovers
Ability: Natural Cure
EVs: 252 HP / 252 Def / 6 SpD
Bold Nature
- Flamethrower
- Toxic
- Wish
- Seismic Toss

 

Scizor (M) @ Choice Band
Ability: Technician
EVs: 6 HP / 252 Atk / 252 Spe
Adamant Nature
- Bullet Punch
- U-turn
- Superpower
- Pursuit

 

Jolteon
Ability: Volt Absorb
EVs: 252 SpA / 6 HP / 252 Spe
Timid Nature
- Thunderbolt
- Shadow Ball
- Hidden Power Ice
- Volt Switch

 

Tyranitar
Ability: Sand Stream
EVs: 252 HP / 252 Atk / 6 Spe
Adamant Nature
- Crunch
- Earthquake
- Thrash
- Rock Slide

 

Dugtrio
Ability: Arena Trap
EVs: 252 Atk / 252 Spe
Jolly Nature
- Substitute
- Earthquake
- Screech
- Reversal