Hello there! I begun making these guides in 2001, back when the game was brand new, and when I could barely sound out the kana on the screen.
Since then, my guides have grown and are much improved! (Taking Japanese in college certainly helps out!) The latest versions are below. (Up to date as of April 10, 2018)
Walkthrough and Translations v2.1
A general guide to the whole game, written for people who cannot read or speak any Japanese.
Card Spoilers and Locations Guide v2.1
A complete guide to the individual cards and where they can be found, along with gameplay notes in some cases.
Quick Ref v1.0
A very bare-bones guide containing information without any fluff. Useful for people familiar with the game who don't want to sift through the huge guide above to find something very specific. Note: this guide was rejected from GameFAQs for being "overspecialized" -- I still find it useful for when I play, so here it is.
Opponent Deck Guide v1.1
Fully lists the contents of every opponent's decks.
Opponent Deck Guide (English patch version) v1.1
Same guide as above, but accommodating the unofficial English patch by including the translated names for new characters and emphasizing the English names rather than the Japanese ones for the whole guide.
Given that it took like ten years to get these guides from version 1 to version 2 (owing to forgetting about it, IRL stuff, etc.) I'm not committing to anything specifically. HOWEVER, I have finally acquired two copies of this game, two Gameboy Colors (with infrared ports), and a Gameboy save reader/writer, so future research will probably be in the direction of CardPop! and link battle stuff.
Possibly some art will appear here, too, scanned and cleaned up from Japanese guides and magazines, if I ever get around to it.