Many of the unique titles for each fighter in Classic Mode contain Easter eggs and references. A few examples are:
*Mario's title "Let's-a-Go" is a reference to one of his phrases.
*Link's title "A Quest to Save Darkness" references the plot of most Zelda games where he's on a mission to seal Ganon away.
*Dark Samus' title "The Great Poison Given Form" references the essence she was created from in the Metroid Prime series.
*Kirby's title "Gourmet Clash" references the Gourmet Race minigame from Kirby Super Star.
*Pikachu's title "I Choose You!" is based off Ash Ketchum's signature catchphrase from the Pokemon Anime, as well as the name of the Anime's first episode.
*Luigi's title "Luigi's Nightmare" is likely a reference to his cowardly personality.
*Ness' title "Home to Onett" is a reference to the Homesick status featured in Earthbound.
*Jigglypuff's title "All Original, All 64" is a reference to the fact that Jigglypuff is a member of the Perfect Attendance Crew for being in every Super Smash Bros. game since the original for the Nintendo 64, and the opponents it faces are against other members of the Perfect Attendance Crew.
Contributed by CuriousUserX90