The damage on fly spread over it’s two turns makes it the least damaging flying type move it can actually learn outside of gust. I would recommend swapping it out for brave bird. Poison Fang should be cross poison. U-turn will benefit it’s insane speed better than haze. Half of the E4 uses hazards and almost all of them have a strategy that relies on status moves. Defog or Taunt are exponentially more useful than confuse ray.
You should only have one mega, especially given the mons in question and the fact that you are running 4 attacks on both. Pick one, slap a choice band on Gallade or choice specs on the D. Gard. They will actually do more damage this way. I’m not sure Gallade needs Earthquake either. It doesn’t hit anything it already can’t and you already have ground moves on two other mons. Maybe swap it out for leaf blade, stone edge or x-scissor?
Are you entirely sold on Machamp? Conkeldurr is basically the same mon but better. If you want Machamp specifically it has two sets.
For no guard you give it an assault vest, Dynamic punch, bullet punch, knock off and stone edge.
For guts (the better set) give it a flame orb Close Combat, bullet punch, knock off and facade.
Volcarona doesn’t need both fiery dance and flamethrower. You should really replace flamethrower with quiver dance. Solar Beam is only good if you are running a sun team. You can tutor it giga drain outside of the ancient tower by diving in Selene City.
Honestly, you are probably going to have some issues. Crobat and Volcarona both lose half of their health to stealth rocks. Half of your team is weak to fairy, flying and rock type, with two of those being quad weak. The only one even capable of wallbreaking the Hippowdon is Mega D. Gard who promptly gets revenge killed by Excadrill, and that’s only if your Gardevoir is modest perfect iv close to max investment sp. atk. His lead could potentially whirlwind you to death with stealth rocks and sandstorm damage.
Aegislash lives anything your Giratina can throw at it unless it shadow sneaks you first and you catch it in offensive form, otherwise you activate it’s weakness policy and it sweeps your team. His Mega Cacturne revenge kills it even if you do get lucky.
You also might have problems with the baton pass team as well.
The champ bodies you as well. His Mewtwo ohko’s you Gallade, Mega D. Gard, Machamp and Crobat. Kyurem and Flygon ohko’s your Giratina, crobat, mega d. gard. His D. Hax ohko’s your Volcarona and mega d. gard.