Ho-Oh appears above Ash in the first Pokémon anime episode’s closing scene.
In “Pokémon, I Choose You!”, Ash sees a large, rainbow-colored Pokémon flying across the sky while he travels toward Viridian City. The Pokémon is Ho-Oh, although Ash and viewers did not initially receive its name or a full explanation of its identity. This brief appearance created an enduring mystery at the very beginning of the series.
Ho-Oh is a Legendary Pokémon associated with the Johto region and Pokémon Gold and Silver. It is a Fire/Flying type and serves as a major legendary counterpart to Lugia. Its rainbow coloration and association with the legendary Rainbow Wing connect it to themes of revival and hope.
The early anime appearance predates Ho-Oh’s formal game debut in Pokémon Gold and Silver. That timing sometimes causes confusion, because Lugia was the title Pokémon of the second film, while Ho-Oh was the mysterious legendary seen in the anime’s opening adventure.