Shiny Mega Gardevoir looks awesome =)
Everything you have on her is fine, just swap Psychic with Psyshock, so she isn't walled by special walls. Hyper Voice is preferred to Moonblast as well, but that move is only available on Black2/White2 move tutors.
Your current Aegislash set is fine, but here's some other ones to take a look at:
https://www.smogon.com/dex/xy/pokemon/aegislash
Sweepers are frail by nature, which is why your Blaziken gets killed easily. You'll wanna try something like this:
-Blaziken w/Focus Sash
Nature: Adamant
Ability: Speed Boost
EVs: 252 Attack, 252 Speed, 4 Sp.Defense
Moves: Flare Blitz, High Jump Kick, Protect, Swords Dance
The idea here is to use Protect to guarantee yourself a Speed Boost, so Blaziken will outspeed most non-Scarfed Pokemon the next turn. Focus Sash is to give an extra turn for it, since most moderately strong neutral attacks will severely damage or KO it. Or to get in a Swords Dance boost. It doesn't
really need any coverage moves since Fire/Fighting is resisted by only a few pokes. The only ones that come to mind are Chandelure and both Giratina forms. So let others handle them.
Guts Swellow isn't the worst thing ever, but its too easily walled by Rock and Steel types. An alternative bird is Staraptor:
-Staraptor w/Choice Band/Choice Scarf
Nature: Jolly/Adamant
Ability: Reckless
EVs: 252 attack, 252 Speed, 4 Defense
Moves: Brave Bird, Double-Edge, Close Combat, U-Turn/Quick Attack
It may not have Talonflame's Gale Wings, but goddamn does this thing hit hard. It also can threaten Rock and Steel types thanks to Close Combat, which Talonflame and Swellow wish they could do.
A Spinner isn't terribly necessary in Battle Spot battles since entry hazards are rarely used. Hazards are generally better in 6v6 battles where there's more switching going on. If it still concerns you, Starmie or Excadrill is the way to go:
-Starmie w/Life Orb
Nature: Timid
Ability: Natural Cure
EVs: 252 Sp.Attack, 252 Speed, 4 HP
Moves: Hydro Pump, Rapid Spin, Thunderbolt/Ice Beam, Psyshock
-Excadrill w/Air Balloon or Leftovers
Nature: Adamant/Jolly
Ability: Mold Breaker
EVs: 252 attack, 252 Speed, 4 Sp.Defense
Moves: Earthquake, Rapid Spin, Rock Slide, Iron Head/Swords Dance
Forretress isn't really all that good because while it can set up and clear away hazards, it can't do much else besides that; its basically dead weight most of the match. Tentacruel I hear isn't so good anymore either, but I'm not sure.
Your team is pretty offensively inclined right now, so you may want to consider adding a defensive/support Pokemon to the team as well.