Tyranitar got Sand Stream. That means that other pokemon than Steel/Ground/Rock types get damaged. And the bad thing is that Tyranitar is the only pokemon who can live in the Sandstorm and the other pokemon in your team get damaged. Tyranitar could easily get OHKO´d before 5 turns with it´s Speed. So i would change Sand Stream to Unnerve so when it switch out your other pokemons doesn´t get hurt. Your main problem with it is the weaknesses. And it haven´t got any moves to help it in it´s situation than switching out. So i would replace Fire Punch with Iron Head to take off the fairy´s or maybe Aerial Ace for T-Tar´s 4x weakness to Fight. As it got good bulk it should be able to strike some hits. I would rather give HP or Def 252 EVs instead of SpDef as you already got Assault Vest. So it´s the only Physical attacker in this team.
Gengar is good not need some inprovements. First change Focus Sash to something like LIfe Orb or Expert Belt. Gengar is very fast and should for the most of the time go first. Add 4EVs to SpDef. If u now choose Life Orb try to get Giga Drain on Gengar instead of Energy Ball to recover some HP. Other than that it´s good with Coverage and power.
Charizard the Mega. It´s great and everything but you need someone who you could pass the Sun too if it faints.so the other 5th and 6th pokemon should do something about it. So it got great moves and everything so it´s fine for the moment.
Espeon with Light Clay. Ok Light Clay can be good but the main problem for this is Mega Gengar or Chandelure. As the both of them got Shadow Tag and is used normal in OU this set is done. I would rather equip Life Orb instead of Light Clay and let someone else take the Screen job. So replace the Screen Moves with Dazzling Gleam and Protect/Substitute for use after Wish. Dazzling Gleam for the Dark types. And as the most sset´s is adding Def Psyshock is good. Remove 16 SpDef EVs and give them to SpAtk for power. And have Modest on it.
Now you need 2 other pokemon and here they come
Trait : Levitate
EVs 252 Spe / 244 SpAtk / 12Hp / 4SpDef
-Psyshock / Psychic
Trait : Sturdy
EVs 252SpAtk / 12SpDef / 244Hp
-Hidden Power [Ice]
So Latias can use Solar Beam in the sun if it happens something with Charizard and got Recover to Heal itself. Magnezone is carrying the Reflect as Defense and Rock types is the bad thing in this team. And it also gets the chance of attacking or setting up Reflect with Sturdy.
Hope I helped