So, according to what I posted before and you picking Rotom-W because that is what your team needed which apparently not.
Either way, looking at your team as a whole it lacks types compatibility and too many mega potentials, you need more diverse coverage.
1st, you would apparently mega the D-Venusaur if you are gonna keep it, making that all other mega potentials in your team mostly not viable. (If not, other options can also be discussed later.)
Typlosion is out and can be replaced by either Talonflame, Blazkin/Infernape, or Volcarona.
Here you got 2 options:
- keep Rotom-W and replace Swampert by either Garchomp, Mamoswine, Gliscor, Hippowdon, Delta Muk or Excadrill.
- keep Sawmpert and replace Rotom-W by either Magnezone, Jolteon, Thundurus, Galventula, Elektross, or Heliolisk.
Flygon is out and can be replaced by either Tyranitar, Weavile, Serperior, Bisharp, Scizor, or Ferrothron.
When you pick a Pokemon make sure no 2 have the same typing at the least, and different coverage from bulk to sweeping, move-pool and abilities utilization.