There is a newer version of the game Monster Rancher 1 & 2 DX that's on Steam, Switch, and iOS... this has a built in CD / Song database so you can access all monsters without being limited to what's on hand. LegendCup.com is fully updated to include the DX changes in the game if you need current resources (Many of the old sites are gone, and many old guides have bits of out-dated info that's been debunked or data-mined since then) and includes the Song Lists for EN and JP versions if you want to jump straight into raising a monster you've never seen or raised before.
Also, the DX remaster has both the JP and EN rares available in the same game, in addition to enemy/boss monsters legally obtainable and are unique playable monsters too! Most of the online tournaments use the newer DX version which is cross-platform and cross-region. However, the Combo Breaker tournament will be played on an emulated PSX version of the game due to logistics. DX needs reliable internet connection to access people's uploaded monsters from around the world and heavily crowded conventions aren't known for their internet reliability. Even if you don't have the PSX version, MooseBones will be converting anyone's qualifying submitted monster from DX into a monster on a PSX game save to be used locally at the tournament.
I'm happy to see even 1 response to this haha.. It's such a niche game/genre I was kind of expecting this to just be an empty echo into the Ether.