Sorry, I don't have the autism to make the stats prime numbers right now.

Mega Nihilego
Rock/Poison
Ability: Levitate
HP: 109
Atk: 53
Def: 67 (+20)
Spa: 167 (+40)
Spd: 146 (+15)
Spe: 128 (+25)

Mega Buzzwole
Bug/Fighting
Ability: Triage
HP: 107
Atk: 179 (+40)
Def: 179 (+40)
Spa: 53
Spd: 73 (+20)
Spe: 79

Mega Pheromosa
Bug/Fighting
Ability: Queenly Majesty
HP: 71
Atk: 167 (+30)
Def: 47 (+10)
Spa: 167 (+30)
Spd: 47 (+10)
Spe: 171 (+20)

Mega Xurkitree
Electric/Grass
Ability: Simple
HP: 83
Atk: 89
Def: 96 (+25)
Spa: 203 (+30)
Spd: 96 (+25)
Spe: 103 (+20)

Mega Kartana
Grass/Steel
Ability: Steelworker
HP: 59
Atk: 211 (+30)
Def: 151 (+20)
Spa: 59
Spd: 61 (+30)
Spe: 129 (+20)

Mega Celesteela
Steel/Flying
Ability: Flash Fire
HP: 97
Atk: 126 (+25)
Def: 128 (+25)
Spa: 132 (+25)
Spd: 126 (+25)
Spe: 61

Mega Guzzlord
Dark/Dragon
Ability: Filter
HP: 223
Atk: 141 (+40)
Def: 103 (+50)
Spa: 97
Spd: 103 (+50)
Spe: 3 (-40)