Reserving Mega Blastoise
This team is great, but it lacks 3 things.
1. Water moves - Fire-types, like Darmanitan, can heavily damage the whole team, (assuming it's the standard set). The team doesn't appreciate Chandulure or Fletchinder all that much either.
2. Hazard Control - Rocks areannoying, especially for Salamence, and other hazards can make this team's day a horrible one.
3. A Mega
So:
->
Blastoise @ Blastoisinite
Ability: Rain Dish -> Mega Launcher
EVs: 52 HP / 252 SpAtk / 200 Spe
Modest Nature
- Scald / Water Pulse
- Ice Beam
- Dark Pulse
- Rapid Spin
This Blastoise can deal with Fire-types that cause issues for this team, like Darmanitan, quite easily with Scald or Water Pulse. Blastoise also provides hazard control, which Salamence can especially appreciate. This also adds another Special Attacker, balancing this hyper offensive team with 3 Physical Attackers and 3 Special Attackers, which lowers the chance of your whole team being walled by one Pokémon at any point. Blastoise is also much bulkier than anything on the team, allowing it to be switch in onto attacks easier than the rest of the team.