|Evolves from||Rayquaza (Knowing Dragon Ascent)|
Mega Rayquaza is a Dragon/Flying-type Legendary Mega Pokémon that Mega Evolves from Rayquaza while knowing Dragon Ascent.
When Rayquaza evolves into Mega Rayquaza, its body becomes longer and gains more features. Its head becomes longer with the Δ symbol appears on its forehead. Its eyes now contain yellow pupils and red irises, and black, tree-like markings trail behind its eyes. Its red lips and teeth become gold, and the gold lines connect to those on its lower horns, which take on a broad, triangular shape. At the outer edges of its lower horns are long, golden, glowing tendrils that each extend to a green, fin-like structure; these tendrils have ring patterns that strongly resemble the yellow markings running along the length of Rayquaza's normal form. Its two upper horns become longer with a gold line running over them in a V shape, and each upper horn has another glowing tendril that ends in a circular shape with a spike. Along the length of its body are golden, glowing orbs placed where its ring patterns used to be. The chin, part of the neck, and parts of its serpentine body are changed to the color black. The fins running along its body are now marked with gold lines; the fins on its tail become entirely yellow and substantially longer.
Particles stream from the long tendrils that extend from its jutting jaw; these particles can control the density and humidity of the air, allowing Mega Rayquaza to manipulate the weather. Its green hide sparkles with an emerald-like quality.