All Mega Evolutions Death Battle Royale

Now its time to see who's the strongest mega evolution ever. And what better way to find out is to have a battle royale between all mega evolutions from X&Y and ORAS.

Mega Venusaur
Mega Charizard (Both X&Y)
Mega Blastoise
Mega Beedrill
Mega Pidgeot
Mega Alakazam
Mega Slowbro
Mega Gengar
Mega Kangaskhan
Mega Pinsir
Mega Gyarados
Mega Aerodactyl
Mega Mewtwo (Both X&Y)

Mega Ampharos
Mega Steelix
Mega Scizor
Mega Heracross
Mega Houndoom
Mega Tyranitar

Mega Sceptile
Mega Blaziken
Mega Swampert
Mega Gardevoir
Mega Sableye
Mega Mawile
Mega Aggron
Mega Medicham
Mega Manectric
Mega Sharpedo
Mega Camerupt
Mega Altaria
Mega Banette
Mega Absol
Mega Glalie
Mega Salamence
Mega Metagross
Mega Latias
Mega Latios
Mega Rayquaza

Mega Lopunny
Mega Garchomp
Mega Lucario
Mega Abomasnow
Mega Gallade

Mega Audino

And finally
Mega Diancie

But who will win, you decide. Because there can be only one winner.

Rules:
1# No EV, IV, or Super training. 
2# No Primal Reversion Pokemon. (Such as Groudon and Kyogre)
3# No TM, HM, Tutor, or Bred moves.