When I first played SSBM (which was my first smash game), I only knew the Mario series, the DK series, the Pokemon series (sort of, the Pokemon they used are (or were) pretty popular so it wasn't hard for you know not to hear about them). And maybe I knew about Kirby.
Edit: I knew about F-Zero, but not Captain Falcon, because I only played the original then.
Also, how I found about each series that I didn't know:
Star Fox - Dunno, really.
Captain Falcon - When I randomly, one day got F-Zero GX on VC, it started by obsession.
LOZ - Randomly got the first LOZ on the VC one day. Eventually got every other game except MM.
Metriod - Besides the general facts, I still have not played or owned a Metriod game. Unless you count the MPH demo.
Fire Emblem - Dunno.
Earthbound - I still haven't plaid it.