That would be Jigglypuff. Wether or not Smash is a true fighting game is debatable, but this little shit has been my main since Melee. I started using her as a joke when me and my friends would play Melee, and this was well before any solid tiering existed, so to us it was just "lol you got fucking stomped by Jigglypuff, fag".
They have nerfed the hell out of her in newer iterations, but I still stick with her because she's still plays almost exactly the same all these years later, I can pick up any Smash but 64 and I'm ready to go. I'm also a largely defensive player when it comes to fighting games, so Jiggs play style definitely fits my niche.
As for an "actual" fighting game character, Siegfried from pretty much any Soul Calibur. I don't care about the character himself, it's all about play style. For Soul Calibur, Sieg tends to be fairly balanced, having a fair bit of speed and damage, but most importantly reach. He doesn't "excel" in any factor, but he's not "middling" in any either, nicely "just above average".
Since I'm a defensive player, being able to play keep away and still chunk HP is extremely important in a battle of attrition and Sieg does this job pretty well while remaining a fairly simple character in overall moveset. There are many better options for speed, power, or reach in SC, but they all tend to sacrifice something else or become far far more complex than the other characters in exchange (or you're just fucking Kilik). I ain't a tournament level player so my only concern is overall efficiency and if I like the play style. It's also just funny when a dude with a comically oversized sword and heavy ass armor beats your ass because he outmaneuvered you, somehow.
