Gameboy Advance SP, although at the time, I didn’t actually have any "traditional" Nintendo games like Mario, Zelda, or Pokemon (I wasn’t even into those franchises yet at the time). I just had games that were tie-ins to movies released at the time like Polar Express, Madagascar, and Cars. Oh, and I had Namco Museum too.
I can’t remember whether I got the Wii or DS next, but it was during those consoles that I started getting into Nintendo stuff.
Hey, I was a Leapster kid too! Thomas was one of my childhood goats.