Groudon

Groudon is a massive, bipedal, dinosaur-like Pokémon covered in red, segmented plates of thick, armor-like skin. It has a gray underside and large white spikes that run along the sides of its head, body, and tail. Groudon has four claws on each hand, four dozer-like blades on the end of its large tail, and three claws on each foot with gray markings under its feet. It also has blue stripes inside the seams of its armor plating which can only be seen when Groudon is glowing with power.

Groudon is believed to be the personification of the land itself, and is described in legends and myths as a "maker of lands" who created the world's continents and expanded the landmasses by generating magma formations. It is also capable of summoning intense sunlight that can dispel rain clouds, evaporate water, and weaken Water-type moves; because of this, it was hailed as a savior for stopping terrible floods. As a super-ancient Pokémon, Groudon is one of the longest-lived species, thought to have lived for thousands of years. It can walk on water by using magma to form a path beneath its feet. Though normally a calm and helpful Pokémon, in olden times, it encountered its rival, Kyogre, and for years, the two engaged in a cataclysmic battle for dominion of the world. They were stopped by the intervention of , who sealed Groudon within Seafloor Cavern under Mt. Chimney, where it has since slumbered underneath the magma. During its sleep, its body is encased in a layer of rock that will be shattered once it is awakened by the Red or Blue Orb. It lives in rough terrain. Groudon loves Groudon Treats made by Snacksworth, who once encountered it in the past. As seen in Hyperspace Desolate Land, Groudon's subconscious takes the appearance of the Cave of Origin.

Forms
Groudon can undergo Primal Reversion and become Primal Groudon. Its appearance remains mostly the same, but it becomes larger and its skin color changes from dark red to deep crimson, with its underside, spikes, and teeth turning black. The blades on its tail are more separated from one another. The Ω symbol can be seen on its arms, and its eyes, the inside of its mouth, and the enlarged openings between its armor plating glow bright yellow. Its irises are also red.

Primal Groudon is said to be Groudon's true, original, and fully powered form, having received its name from the ancient people of the Hoenn region who it tormented in the past. The energy that fills it pours forth as magma, and it burns with such an extreme temperature that its body is always shimmering with the haze of its heat. Primal Groudon and Primal Kyogre fought each other over the natural energy that was abundant in the primal age millennia ago; one of their clashes lasted for 20 days straight and threatened to disrupt the planet's balance and destroy it before Rayquaza stopped them. Research data from the Weather Institute indicates that Primal Groudon has the power to eliminate all life before initiating a reset of the planet. It was formed from the natural primal energy that existed in Hoenn's ancient past, which it has to feed on so it can maintain its transformation in the present day after it was undone by Mega Rayquaza. Due to the lack of natural energy in the surface, it is forced to find either a source underground, such as the stones in the Cave of Origin, or the Red Orb, which contains the remaining energy of the primordial world, allowing it to undergo Primal Reversion. With its weather-manipulating powers, Primal Groudon can outright nullify Water-type moves rather than simply weaken them. In the Mega Evolution Pokédex Short, it is said to create new land with every step it takes.

(Source: Bulbapedia)