64 - My grandparents bought it for me.
Melee - Same as 64, I think.
Brawl - I believe my parents bought it for me; we first rented it from our town's Movie Gallery when it was still a thing. It was my first Smash game; well, the first one I have clear-ish memories of; technically 64 was my first, but I played it on a machine in a hospital I was staying in when I was young, so while I remember playing it alongside a Winnie the Pooh game, I pretty much only know it was Smash because I remember a character that may have been Samus. Funnily enough, my memory of the Winnie the Pooh game is much clearer, although I still don't remember much of what I did in its level.
3DS / Wii U - Either my parents or grandparents got the 3DS version for me around when it released or for my birthday; Wii U may have been for Christmas or near the end of November, but it was after when I got the 3DS version, and my parents got it for me.
Ultimate - My grandmother got it for me, the physical release; it may come in on my birthday, but that's when it releases so I'm not sure.