I got into Smash because I was already a fan of Mario, Yoshi, Donkey Kong, Kirby, Pikachu, and Link. (we had an SNES and Game Boys, and our Nintendo 64 came with Banjo-Kazooie and Ocarina of Time) I think I had seen a friend of mine play Star Fox 64, so I was aware of Fox at the time. The original Smash Bros. was the first non-bundled N64 game that we got.
I can't recall if Smash made me want to play Metroid (I think I was aware of what Metroid was at the time, though my SNES was a hand-me-down that we got near the end of the system's lifespan and I didn't have much disposable income, so there weren't many opportunities to buy Super Metroid), but at the very least, the Smash games got me to play the following:
64: F-Zero, Earthbound (though for Earthbound, I waited until it came out on the Wii U's virtual console - just the cartridge alone (not including the box, strategy guide, etc.) was $200, and for whatever reason, I have trouble with getting into RPGs when using less-than-legal methods)
Brawl: Metal Gear (I ordered Metal Gear Solid: The Twin Snakes off of eBay, which was rare for me)
Smash 4: Fire Emblem, Kid Icarus (I bought a 3DS, both for Smash and because I anticipated that we'd get characters from those games. There was a new Fire Emblem character in every Smash game, and Sakurai worked on Kid Icarus so getting something like that seemed like a guarantee), Xenoblade (I think I bought the game before Shulk was announced, though part of it might have been anticipating that someone from the Operation Rainfall games might be added - another part was its rarity and EB Games exclusivity)
Ultimate: Dragon Quest (at the very least, it motivated me to pick it up again - I bought 8 when it came out on the 3DS, but my backlog's gotten pretty big), Castlevania (Symphony of the Night, specifically - wanted to find out who Richter was, and playing the Metroid games is where the series clicked for me), Persona (I had bought 5, since it was critically-acclaimed and on sale, but Joker's Smash announcement motivated me to play it. 100+ hours later, I'm definitely a fan of the series now)