[RATE MY TEAM] Need help for my team

[Marcusube]

Sableye-Mega @ Sablenite
Ability: Magic Bounce
Level: 50
EVs: 252 HP / 108 Def / 148 SpD
Bold Nature
- Will-O-Wisp
- Calm Mind
- Dark Pulse
- Recover

Dragalge @ Black Sludge
Ability: Adaptability
Level: 50
EVs: 244 HP / 156 Def / 20 SpA / 88 SpD
Sassy Nature
- Draco Meteor
- Sludge Wave
- Scald
- Substitute

Skarmory @ Rocky Helmet
Ability: Sturdy
Level: 50
EVs: 244 HP / 236 Def / 28 SpD
Impish Nature
- Stealth Rock
- Brave Bird
- Whirlwind
- Roost

Gardevoir @ Choice Scarf
Ability: Trace
Level: 50
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
- Energy Ball
- Psyshock
- Moonblast
- Shadow Ball

Diggersby @ Choice Scarf
Ability: Huge Power
Level: 50
EVs: 4 HP / 252 Atk / 252 Spe
Adamant Nature
- Earthquake
- Return
- Knock Off
- U-turn

Slowbro @ Leftovers
Ability: Regenerator
Level: 50
EVs: 244 HP / 252 Def / 12 SpD
Bold Nature
- Calm Mind
- Slack Off
- Scald
- Fire Blast

Your team is solid, however, it has a lot of weaknesses. Generally, it is able to switch in and out without any trouble but you need to watch out for those Dark and Ice types since there isn't really much on your team that can tank these attacks. Overall, nice team and I hope you consider my suggestions