The 3DS version of the game is the only port that lacks the opening intro once the game is booted. This was probably done to save space on the game cartridge.
Sources:
Smash 3DS - This game doesn't even have an intro... | Smashboards
Super Smash Bros. for Nintendo 3DS - SmashWiki, the Super Smash Bros. wiki (ssbwiki.com)
Sources:
Smash 3DS - This game doesn't even have an intro... | Smashboards
Super Smash Bros. for Nintendo 3DS - SmashWiki, the Super Smash Bros. wiki (ssbwiki.com)