Okay... it's been 20 years, I'll admit it: that's exactly it ahahaha
While I did get a "How to Hack Like a Pro!" VHS tape (which I still have!) with my GameShark CDX, I didn't understand any of that shit. Actually I'm not sure if it was even possible to do anything productive with the CDX, you might've needed a Gameshark Pro for that. So all I could do was fuck around with the addresses and values that others provided, mix + match them, and try to put them together in ways that others hadn't yet and/or word things creatively.
Anyway, I just discovered that my old SD2 Hacking site is almost fully archived thanks to the Wayback Machine. Yes, that's right. Somehow despite losing countless creations and websites over the 2000s, including ALL of my Fire Pro animations, my old SD2 site from July 2001 still exists. Check it out here.
Pretty much all the images from the SD2 Cheats pages still work, but I also uploaded them to an Imgur album for convenience here: https://imgur.com/a/FGQTd2G
Ah, memories.
Also, EpyonZeroX didn't do shit - he was just a friend I'd give partial credit to in arbitrary amounts. You'll find that some of the codes on my site give 75% credit to myself and 25% to him.
Not sure what I got out of doing that. Maybe it made me feel like I had some authority, or maybe I was trying to mimic the teamwork I saw going on with some of the more legit codes. Who knows - I was 13!