I would like advice on team building :)

[R2D2]

Hello!

I am new to this thread, and i would like to ask for some advice for the super single subway as well as random online matchup (a proper team build would be nice)
For some reason i tend to almost only train sweepers :P for their sheer power. However, this often makes me lose to pokemon with items like choice scarf or just super effective priority moves like ice shards and stuff like that. I would like some advice on how to construct a team with some pokemon i have already trained, plus some Pokemon that would be nice to increase my longevity in battles.
Below i will list the poke's i have at lvl 100 ATM with maxed EV's and moves. Feel free to also give some advice on the movesets. I have most tm's and enough shards to change move sets around. I would also like to know which items would be best to use. Thanks in advance

What i have :

Dragonight 252 Attack/4 spd/252 spe (pure dragon dance sweep)
Adamant nature
Ability : multiscale
Outrage
Fire punch
Extreme speed
Dragon dance

Scizor 252 attck/252 spe/4 hp
Adamant nature
Ability : Technician

Bullet punch
Bug bite
Superpower
Swords dance

Starmie 252 spe/ 252 spa/4 spd
Timid nature
Ability : Natural cure

Surf
Psyshock
Thunderbolt
Ice beam


Gastrodon 252 hp/252 spd/ 4 def
Sassy nature
Ability : Storm drain

Ice beam
Earth power
Recover
Toxic

Dugtrio : 252 attack/ 32 def / 224 spe
Jolly nature
Ability : arena trap

Earthquake
Sucker punch
Substitute
Stone edge

Gyarados 156 hp/128 attck/204 spe
Adamant nature
Ability : intimidate

Waterfall
Dragon dance
Taunt
Bounce

i could try with pokes i have : calm mind Raikou, eviolite porygon, specially defensive milotic, Sweeper mamoswine.

These are some of the better ones i have, but as you can see, and as i said at the beginning of this post, most of them are sweeper oriented. I dont mind training some new pokes. Even if i were to use only one of these in my new team. I would like any suggestions on proper additions to increase my choice of pokemon to use. If you are able to construct a proper team out of these, by using them as they are. Or by changing some moves (adding items) please tell me . Im having trouble getting consecutive wins. Especially in random matchup. My win streak in super single is till now only 28.

[R2D2]

I have made the list of poke's i placed shorter, so it is only one team of 6 atm.
I would still like to know what to take to random matchup and super single sub.