I would suggest swapping out Mega-Tyranitar for Lando-T or Togekiss or Talonflame because they pair up with Mega-Gyarados better than Raichu or Rotom-Heat so Mega-Gyarados can freely Earthquake or swap out Mega-Gyarados for a Bulky water pokemon like suicune or milotic to pair up with Mega-Tyranitar. The reason for this swap is because 2 mega teams must have 4 other pokemon have synergy with both megas for example Raichu is only good with Gyarados and Azumarill with Tyranitar.
I would suggest with the current team that...
Gyarados have Protect. Also might put leftovers/lum berry if you want to keep Mega-Tyranitar and keep Gyarados
A different spread for Rotom-Heat like 200hp 112def 96satk 72sdef 28speed which allows Rockslides to be 3OHKO and it can take Scalds from everything including Politoed in Rain (60 SpA Politoed Scald vs. 200 HP / 72+ SpD Rotom-H in Rain: 108-128 (72 - 85.3%) -- guaranteed 2HKO)
I would suggest with the current team that...
Gyarados have Protect. Also might put leftovers/lum berry if you want to keep Mega-Tyranitar and keep Gyarados
A different spread for Rotom-Heat like 200hp 112def 96satk 72sdef 28speed which allows Rockslides to be 3OHKO and it can take Scalds from everything including Politoed in Rain (60 SpA Politoed Scald vs. 200 HP / 72+ SpD Rotom-H in Rain: 108-128 (72 - 85.3%) -- guaranteed 2HKO)
