Arceus

Arceus will use Gravity to slam down any nearby airborne opponents. If you aren't on a platform, you will get dunked off the stage. Arceus (, Arceus) is a creature from the series.

Origin
Arceus is a introduced in, and is listed at #493 as the final Pokémon in that generation's National Pokédex, being categorized as the "Alpha Pokémon". In the Sinnoh mythos, it is considered the universe's creator, and the master of the generation's two legendary trios. By holding a matching item, it can change its type from Normal to any other type in the game. Its signature move is, an attack which changes its type to match Arceus's current type. Arceus played a major role in .

is a non-damaging Psychic-type move introduced in Generation IV. When used, it applies a status effect to the battlefield for 5 turns, grounding every Pokémon on the field: this lowers the evasion of all Pokémon by two stages, removes any immunity to Ground-type moves and makes some moves like impossible to perform. Arceus learns Gravity at level 10, but since every legitimately available Arceus thus far was only obtainable at much higher levels, Arceus requires a or  to learn the move.

As a Poké Ball Pokémon
Arceus appears as a Poké Ball and a Master Ball summon. When summoned, it produces a large shockwave that acts as a powerful long-range meteor smash. It does so three times, with a short delay between each use, before disappearing. Only airborne players will be hit; grounded players are not affected. It does not cause damage, but it possesses very powerful set knockback, which is very likely to KO any off-stage opponent. However, opponents can potentially DI towards a stage wall, allowing them to tech and survive. The launch rate can affect how powerful the attack is.

When Arceus is out, CPUs will prefer to stay grounded. If they are on a platform far away from other fighters, they will remain there, spamming attacks.

Trophy
In the Arceus trophy is part of the Legend of Pokémon Diamond & Pokémon Pearl.

As a Poké Ball Pokémon
Arceus reappears as a Poké Ball and Master Ball Pokémon. The knockback dealt by the attack is no longer set.

Arceus cannot be summoned on Arena Ferox, Balloon Fight, Brinstar, Corneria, Dream Land GB, Jungle Japes, Living Room, Magicant, Onett, Reset Bomb Forest, Spirit Train, Super Mario Maker, Suzaku Castle, Tortimer Island, WarioWare Inc., or Yoshi's Island.

Spirit
Arceus also appears as a Legend-class primary spirit.

In Adventure Mode: World of Light, Arceus is presumably one of the countless spirits captured by Galeem during his takeover of the universe. After Galeem's defeat, Dharkon takes control of Galeem's spirits, including Arceus. After Dharkon's defeat, he flees to the final world, with Galeem following soon after. In the final world, Galeem and Dharkon wage war against each other using their captured spirits, with Galeem taking control of Arceus.

Arceus uses a puppet fighter and is fought on the Spear Pillar stage. During the battle, Arceus is summoned while heavy winds are immediately in effect, referencing Arceus's  move. Also, Corrin's dragon form highly resembles Arceus, and Corrin's Japanese name, "Kamui", is the Ainu word for "god", referencing how Arceus is the creator of the Pokémon world.

Trivia

 * The base stats of the Arceus Spirit are both 2006, which is the year Pokémon Diamond and Pearl were released in Japan.
 * On Jungle Hijinxs, characters not on the plane that Arceus is on will not be affected by Gravity.