This sound comes from the character reveal style popularized by Super Smash Bros., especially the “joins the battle” presentation used in Nintendo promo videos and fan edits. Online, creators turned that format into a reusable template for introducing anyone from friends and pets to fictional characters and inanimate objects. It spread widely in short edits, reaction memes and parody trailers because the structure is instantly recognizable and gives even a low-stakes reveal a dramatic, game-like entrance. That same roster-style hype keeps it relevant years later.