Aerodactyl-Mega (M) @ Aerodactylite
Ability: Pressure
Shiny: Yes
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Aerial Ace
- Hone Claws
- Fire Fang
- Aqua Tail

Shuckle (F) @ Mental Herb
Ability: Sturdy
Shiny: Yes
EVs: 252 HP / 92 Def / 164 SpD
Careful Nature
- Sticky Web
- Stealth Rock
- Knock Off
- Encore

Kabutops (M) @ Life Orb
Ability: Swift Swim
Shiny: Yes
EVs: 252 Atk / 4 Def / 252 Spe
Naive Nature
- Waterfall
- Rapid Spin
- Stone Edge
- Aqua Jet

Cradily (F) @ Leftovers
Ability: Storm Drain
EVs: 180 HP / 200 Def / 128 SpA
Bold Nature
IVs: 0 Atk
- Toxic
- Recover
- Giga Drain
- Mirror Coat

Terrakion @ Choice Scarf
Ability: Justified
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Close Combat
- Stone Edge
- Earthquake
- Poison Jab

Tyranitar (M) @ Assault Vest
Ability: Sand Stream
EVs: 248 HP / 212 SpA / 48 Spe
Modest Nature
IVs: 0 Atk
- Dark Pulse
- Flamethrower
- Thunderbolt
- Ice Beam
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Original ^^^
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Revision vvv
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Aerodactyl-Mega (M) @ Aerodactylite
Ability: Pressure
Shiny: Yes
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Aerial Ace
- Hone Claws
- Fire Fang / Stone Edge
- Aqua Tail
I think an important change here would be Jolly Nature -> Adamant Nature. You don't miss out on any important Speed tiers, and the power makes a big difference.

Jolly
     252 Atk Tough Claws Mega Aerodactyl Aerial Ace vs. 0 HP / 4 Def Keldeo: 288-338 (89.1 - 104.6%) -- 31.3% chance to OHKO
Adamant
     252+ Atk Tough Claws Mega Aerodactyl Aerial Ace vs. 0 HP / 4 Def Keldeo: 314-372 (97.2 - 115.1%) -- 81.3% chance to OHKO
Like, now you can revenge Keldeo immediately! o3o
     252+ Atk Tough Claws Mega Aerodactyl Aqua Tail vs. 0 HP / 0 Def Terrakion: 316-372 (97.8 - 115.1%) -- 81.3% chance to OHKO
Same with Terrakion.
Optional, using Stone Edge over Fire Fang is also nice if you want another good STAB to use. Hone Claws increasing Stone Edge's accuracy is also super nice too. However, hitting Ferrothorn with Fire Fang is also good, so if you want, just keep Fire Fang.

Shuckle (F) @ Mental Herb
Ability: Sturdy
Shiny: Yes
EVs: 248 HP / 252 Def / 8 SpD
Impish Nature
- Sticky Web
- Stealth Rock
- Knock Off
- Encore
I changed your EV spread to one that's fully invested in Defense. Take less from Ground- and Fighting-types, that's where it counts. If you need SpD, you can always use TTar's Sand.

Omastar @ Air Balloon
Ability: Weak Armor
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk / 30 SpA
- Shell Smash
- Scald
- Ice Beam
- Hidden Power [Grass]
This is one of the bigger changes. I think you should give Omastar a try over Kabutops. Your current team lacks powerful special attackers (ttar doesn't quite cut it) and Omastar gives you a useful wincon against some teams, but most importantly Ground. In a pinch you can also use this to help beat Mega Sableye, but it's not the best check out there.

Cradily (F) @ Leftovers
Ability: Storm Drain
EVs: 252 HP / 252 Def / 4 SpA
Bold Nature
IVs: 0 Atk
- Toxic
- Recover
- Giga Drain
- Mirror Coat
Minor change, changed the EV spread to one that's completely physically defensive. Countering Landorus-T, Garchomp, and Mega Swampert more comfortably is more important. What were the SpA EVs for?

Terrakion @ Choice Scarf
Ability: Justified
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Close Combat
- Stone Edge
- Earthquake
- Iron Head
Changed Poison Jab to Iron Head. More useful against Fairies, no immunities, reliable, yeah .3. If you want to keep PJab to hit azumarill, that's fine too. Iron Does have a nifty flinch chance though.

Tyranitar (M) @ Assault Vest
Ability: Sand Stream
EVs: 248 HP / 212 SpA / 48 Spe
Modest Nature
IVs: 0 Atk
- Dark Pulse
- Flamethrower
- Thunderbolt
- Ice Beam
Sorry, I have no idea how this set works in Mono. I don't have much input here xp.