Mega Charizard Y Sun Team

[Slec]

This looks like a pretty solid team on paper. The only concern I have is with the ev spreads on some of the pokemon. Aegislash should NOT be 252/252/4. It needs to take advantage of its defenses rather than offenses. I suggest this set

Aegislash (F) @ Weakness Policy
Ability: Stance Change
EVs: 252 HP / 108 Def / 128 SpA / 20 SpD
Sassy or Calm Nature (depending on trick room)
-Shadow Ball
-Flash Cannon
-King's Shield
-Wide Guard

here are some damage calculations for it:
252+ Atk Life Orb Talonflame Flare Blitz vs. 252 HP / 108 Def Aegislash-Shield: 140-166 (83.8 - 99.4%) -- guaranteed 2HKO
252 Atk Life Orb Bisharp Knock Off (97.5 BP) vs. 252 HP / 108 Def Aegislash-Shield: 140-166 (83.8 - 99.4%) -- guaranteed 2HKO
252+ SpA Choice Specs Hydreigon Dark Pulse vs. 252 HP / 20+ SpD Aegislash-Shield: 138-164 (82.6 - 98.2%) -- guaranteed 2HKO
252+ SpA Rotom-H Overheat vs. 252 HP / 20+ SpD Aegislash-Shield: 134-158 (80.2 - 94.6%) -- guaranteed 2HKO
116+ SpA Mega Charizard Y Heat Wave vs. 252 HP / 20+ SpD Aegislash-Shield in Sun: 134-162 (80.2 - 97%) -- guaranteed 2HKO

Next is Hitmontop which is an interesting pokemon. With intimidate it already has an advantage with physical attackers so you should invest more in special defense. Here is a set for it:
Hitmontop @ Sitrus Berry
Ability: Intimidate
EVs: 252 HP / 136 Atk / 60 Def / 60 SpD
Adamant Nature
- Fake Out
- Close Combat
- Quick Guard/Wide Guard/Protect
- Protect/Wide Guard/Quick Guard

And finally Garchomp which is a huge threat that you need to keep alive. Garchomp has some bulk to it so really just maxing out stats isnt necessary at all. Try this:

Garchomp @ Rocky Helmet / Roseli Berry / Lum Berry
Ability: Rough Skin
Adamant Nature
12 HP / 232 Attack / 36 Special Defense / 228 Speed (12 HP / 198 Attack / 36 Def / 36 Special Defense / 228 Speed if using Roseli Berry)
- Dragon Claw
- Earthquake
- Rock Slide
- Protect