Mega Rayquaza Confirmed
|His yellow "tattoos" now|
float beside him like ribbons.
"It was a primal age, early in the world's history... The natural world was overflowing with energy. That energy granted Groudon and Kyogre an overwhelming power. Seeking ever more of that energy for themselves, the two clashed again and again, and their battles cast the people and Pokémon of Hoenn into great danger. Brimming with the overwhelming power granted by the energy of nature, this transformation was named by later people "Primal Reversion." And the people called their tormentors Primal Groudon and Primal Kyogre.This shows that unlike the other two, Rayquaza mega evolved at the request of humans (with the "great stone [...] with rainbow brilliance likely being a giant Keystone). Mega Rayquaza gets the new weather ability Delta Stream. This ability overwrites any currently in effect weather as well as blocks weather moves (like Sunny Day) and weaker weather abilities (like Drought). The new weather type also reduces damage from moves on Flying pokémon to normal damage. The weather is removed if Desolate Land or Primordial Sea is activated second or if Mega Rayquaza is switched out. It also learns a new flying move, Dragon Ascent, which is likely a variant of Overheat.
One Pokémon looked down upon this battle from the sky above. The Pokémon that dances in the heavens: Rayquaza. Rayquaza is venerated by the people of Hoenn as their protector and savior. When Primal Groudon and Primal Kyogre had battled for 20 dawns and 20 nights, the world began to lose its natural balance and tilt toward destruction. The people, unable to endure any more, cried out to their mighty savior Rayquaza before a great stone that shone with rainbow brilliance. And a change came upon Rayquaza, weaving in the sky above Primal Groudon and Primal Kyogre. Suffused in brilliant light, its body began to transform visibly. And then..."