My team

I'm pretty new to online battling, but I'm looking to build a competetive team for online play and would like some feedback

I currently have

Tyranitar@Choice Band
Adamant
Ability: Sand Stream
EVs: 180 HP / 252 Atk / 76 Spd
-Stone Edge
-Aqua Tail
-Crunch
-Pursuit

Garchomp@Yache berry or Life Orb
Jolly
Ability: Sand Veil
EVs: 252 Atk / 252 Spd
-Earthquake
-Fire Fang
-Swords Dance
-Outrage

Basicly I think both Tyranitar and Garchomp go both well together, because of the sandstorm.
And both seem to be good physical sweepers

Scizor@life orb
Adamant
Ability: Technician
EVs: HP 252 / Atk 252
-Swords Dance
-Bug Bite
-Bullet Punch
-Roost

I picked HP over Speed on Scizor, because I assume I'll go with 1 Swords Dance the first round and future rounds I'd go with bullet punch most of the time making Speed EV less useful seeing how Bullet Punch is a priority move afterall.

Jolteon@damp rock
Timid
Ability: Volt Absorb
EVs: S.Atk 252 / Speed 252
-Rain Dance
-Baton Pass
-Thunder
-Thunder Wave

He's basicly my special sweeper, but also to criple the oponent if needed if both I can also rain dance to boost thunder accuracy assuming Tyranitar is alive or if both Tyranitar and Garchomp are dead sandstorm doesn't matter anymore.

Kingdra @Choice Specs
EVs: 252 S.Atk / 252 Speed
Modest
Ability: Swift Swim
-Hydro Pump
-Draco Meteor
-Dragon Pulse
-Ice Beam

Another Special sweeper combined with Jolteon's Rain Dance

Blissey@Leftovers
Bold
Ability: Natural Cure
EVs: Def 252 / HP 252
-Flame thrower
-Softboiled
-Toxic
-Wish

Pretty much special wall for any special sweepers.

That's my current team, any help/comments/feedback appreciated I'm still pretty noob when it comes to competitive battling :D

It seems like you're going for a bulky SD Scizor. This set is meant to survive multiple hits and set up multiple SDs:
-Swords Dance
-Bullet Punch
-Bug Bite/Superpower/Brick Break
-Roost
Nature: Adamant
EVs: 252 HP/40 Atk/216 SDef
Item: Leftovers
Ability: Technician

While it's true that SS won't matter if Garchomp and Tyranitar go down, having rain-oriente Pokémon won't seem like a good fit while the Sand is going. Jolteon has poor defenses and suffers from Sandstorm. I'd add in Ferrothorn for an additional sand immunity, hazard support to help Tyranitar and Garchomp nail OHKOs/2HKOs without wasting additional PP, and check to Rain teams, as well as Gastrodon or Rotom-W for backup checks:

Ferrothorn:
-Stealth Rock/Spikes
-Leech Seed
-Power Whip
-Gyro Ball/Thunder Wave/Protect
Nature: Relaxed
EVs: 252 HP/88 Def/168 SDef
Item: Leftovers

Rotom-W:
-Volt Switch
-Hydro Pump
-Will-o-Wisp
-Pain Split/Hidden Power (Ice)
Nature: Modest
EVs: 232 HP/56 SAtk/220 Spe
Item: Leftovers

or
-Volt Switch
-Hydro Pump
-Will-o-Wisp/Thunder Wave
-Pain Split
Nature: Calm
EVs: 248 HP/28 SAtk/232 SDef
Item: Leftovers

or
-Volt Switch
-Hydro Pump
-Hidden Power (Ice)
-Trick/Thunderbolt
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Specs/Choice Scarf

Gastrodon:
-Earthquake/Earth Power
-Scald/Ice Beam
-Toxic
-Recover
Nature: Sassy/Calm
EVs: 252 HP/84 Def/172 SDef
Item: Leftovers
Ability: Storm Drain

or
-Surf
-Earth Power
-Ice Beam
-Recover/Hidden Power (Grass)
Nature: Modest
EVs: 124 HP/252 SAtk/132 SDef
Item: Leftovers
Ability: Storm Drain

Even with the changes I made, I noticed you're seriously screwed over by Breloom. Gengar, Celebi or Latias should help at least check it.

Gengar:
-Substitute
-Shadow Ball
-Focus Blast
-Disable/Pain Split/Thunderbolt/Hidden Power (Fire)
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Black Sludge/Life Orb

or
-Substitute/Protect
-Shadow Ball
-Focus Blast
-Hidden Power (Fire)
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb/Black Sludge

Latias:
-Calm Mind
-Dragon Pulse
-Recover
-Substitute/Hidden Power (Fire)/Psyshock
Nature: Timid
EVs: 252 HP/4 SAtk/252 Spe
Item: Leftovers

or
-Draco Meteor
-Psyshock
-Surf/Hidden Power (Fire)
-Recover/Trick
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb/Choice Specs

Celebi:
-Giga Drain/Psychic
-Recover
-U-turn
-Perish Song/Thunder Wave/Stealth Rock
Nature: Calm
EVs: 252 HP/236 SDef/20 Spe
Item: Leftovers

or
-Leaf Storm
-Earth Power/Psychic/Hidden Power (Fire)
-Thunder Wave/U-turn
-Recover
Nature: Modest
EVs: 56 HP/252 SAtk/220 Spe
Item: Life Orb/Leftovers

or
-Nasty Plot
-Giga Drain
-Earth Power/Hidden Power (Fire)
-Psychic/Recover/Hidden Power (Ice)
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb/Leftovers

or
-Leaf Storm
-Hidden Power (Ice/Fire)
-Earth Power/Psychic
-U-turn/Trick
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Scarf

Thanks for the awesome feedback PlatinumDude, currently I chose to go with these 3 which you mentioned. I am still trying out different moves, but not exactly how you mentioned

Ferrothorn @ Leftovers
Trait: Iron Barbs
EVs: 252 HP / 88 Def / 168 SDef
Relaxed Nature
- Thunder Wave
- Leech Seed
- Power Whip
- Stealth Rock

Pretty awesome wall for dragons/water. While being able to criple the oponent with Para and also stealth rock.

Gastrodon @ Leftovers
Trait: Storm Drain
EVs: 252 HP / 84 Def / 172 SDef
Calm Nature
- Toxic
- Scald
- Recover
- Ice Beam

Gastrodon over Rotom-W. Occasianlly can trick people into using water attacks on Tyr or if they have a rain dance team and then switch to Gastrodon. Went and went with icebeam instead of earth cause I currently have Garchomp covering earth and ice does help vs dragons.

Celebi @ Leftovers
Trait: Natural Cure
EVs: 252 HP / 236 SDef / 20 Spd
Calm Nature
- Recover
- U-turn
- Psychic
- Giga Drain

Pretty useful taking fighting hits + having physic is nice versus fighting types which Ferrorthorn and Tyranitar are weak to.