Extrasensory > U-turn on Greninja; dealing with Mega Venusaur could be helpful.
King's Shield + Swords Dance Aegislash is horrible. It's walled easily and crippled by burn. You don't get how Stance Change works, do you? It simply lets Aegislash switch forms, which share the same EVs between one another. It's best to use offensive spreads on it as a result:
-Shadow Ball
-Shadow Sneak/Sacred Sword
-Iron Head/Sacred Sword/Pursuit
-King's Shield
Nature: Quiet
EVs: 244 HP/12 Def/252 SAtk
Item: Leftovers/Spooky Plate/Spell Tag/Air Balloon
or
-Substitute
-Toxic
-Shadow Ball
-King's Shield
Nature: Modest
EVs: 244 HP/12 Def/252 SAtk
Item: Leftovers
or
-Shadow Ball
-Shadow Sneak
-Flash Cannon/Sacred Sword
-Pursuit/Sacred Sword
Nature: Hasty/Naive
EVs: 4 Atk/252 SAtk/252 Spe
Item: Life Orb
or
-Swords Dance
-Shadow Sneak
-Shadow Claw/Iron Head
-Sacred Sword/Head Smash
Nature: Adamant
EVs: 252 Atk/4 SDef/252 Spe
Item: Life Orb
Fire Blast > Flamethrower on Charizard Y. It provides more power, while still being reasonably accurate. Put the last 4 EVs into either defensive stat; putting them in HP makes them even, making Charizard die to 2 Stealth Rock switch-ins.
Goodra's Rain conflicts with Charizard's Drought. Rain stalling is highly ineffective this generation because of the rain nerf to Drizzle. Instead, Goodra can act as a bulky Assault Vest sponge:
-Draco Meteor
-Fire Blast
-Thunderbolt/Earthquake
-Dragon Tail/Earthquake
Nature: Quiet/Sassy
EVs: 248 HP/252 SAtk/8 SDef
Item: Assault Vest
Ability: Gooey/Sap Sipper
Donphan is outclassed by Excadrill as a Rapid Spinner because the latter hits harder and has more reasonable Speed:
-Earthquake
-Iron Head
-Rapid Spin
-Rock Slide/Stealth Rock
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Leftovers/Air Balloon
Ability: Mold Breaker
or
-Earthquake
-Iron Head
-Rock Slide
-Rapid Spin
Nature: Adamant/Jolly
EVs: 252 Atk/4 Def/252 Spe (Choice Scarf) or 120 HP/136 Atk/252 SDef (Assault Vest; Adamant only)
Item: Choice Scarf/Assault Vest
Ability: Mold Breaker