Your team is apparently OU (you tagged it OU), but it has literally no OU pokemon, although I guess Gengar is sort of OU because people run him a lot in OU. No OU pokemon in OU isn't going to get you anywhere. Here's your team, but fixed:
Gliscor @ Toxic Orb
Ability: Poison Heal
Adamant Nature
EVs: 184 HP/72 Spe/252 Atk
- Swords Dance
- Protect/Roost
- Earthquake
- Facade
Description: sumwun said that Roost was better than Protect on offensive Gliscor, but I disagree as Protect allows you to scout out your opponent for Ice Moves and allows you to stall one turn to guarantee that the Toxic Orb will activate. Stone Edge did offer some coverage in killing Flying Types that otherwise would wall Gliscor as they are unnefected by EQ, but Facade has insane damage with the Toxic Orb and SD, so I chose it over Stone Edge. In short, try not to scream when your opponent sends in Mega Pidgeot.
Toxapex @ Black Sludge
Ability: Regenerator
Calm Nature
EVs: 252 HP/252 SpD/4 Def
IVs: 0 Atk
- Scald
- Toxic Spikes
- Haze
- Recover
Description: Replacement for Tentacruel. Does everything it can, and better. Better stats, movepool, ability, access to reliable recovery, and gets Haze.
eXcess (Scizor-Mega) @ Scizorite
Ability: Light Metal----->Technician
Impish Nature
EVs: 248 HP/252 Def/8 SpD
- Swords Dance
- Bullet Punch
- Knock Off
- Roost
Description: Much better mega than Manetric, the only real problem is Fire Types.
Heatran @ Leftovers/Air Balloon
Ability: Flash Fire
Timid Nature
EVs: 252 Spe/252 HP/4 SpD
IVs: 0 Atk
- Magma Storm
- Earth Power
- Protect
- Taunt
Description: Works really well with Scizor-Mega, much better fire type than Talonflame, and is an absolute tank. 252 speed EVs is to outspeed other Scizor-Megas, and more.
Skarmory @ Leftovers
Ability: Sturdy
Impish Nature
EVs: 248 HP/252 Def/8 SpD
- Brave Bird
- Roost
- Spikes
- Whirlwind
Description: Much, much better tank than Chestnaught, and no obnoxious 4x weakness. The amount of steel types on this team IS a little bit disturbing, but Heatran covers for Fire, and Skarmory for Ground, so I think we're OK.
Gengar @ Choice Specs/Choice Scarf
Ability: Cursed Body
Timid Nature
EVs: 252 Spe/252 SpA/4 SpD
IVs: 0 Atk
- Shadow Ball
- Sludge Wave
- Trick
- Focus Blast
Description: Trick can very easily shut down tanks and physical attackers, and although Specs is the preffered item, you might want to run Scarf to suprise kill Tapu Koko.
CONCLUSION - This team gets destroyed by banded Zygarde with Thousand Arrows, but other than that I think it's OK.