Ness turns up in every Super Smash Bros. game from Melee to Ultimate, but the series he comes from is far stranger than his cameo status suggests. EarthBound (1994) sends a young boy on an adventure through a land based on the USA, full of quirky characters and strange locations, and at 9.1 it remains the high point. Mother 3 (2006) runs it close at 9.0, while EarthBound Beginnings, the once Japan-only original, finally saw a wider release in 2015.
EarthBound itself is the place to start: a turn-based JRPG whose real subject is tone, sincere and silly at once. Mother 3 is the follow-up for the converted, and Beginnings (8.1) is the rougher historical artifact. This is a tiny series that punches far above its size, kept visible for decades mostly by those Smash Bros. guest slots.
The Earthbound franchise spans 3 games in the CrossBinge catalog.