I noticed that there is no submission for Wii as a platform. Would that be because there is not much difference at all and Wii therefore falls under GC as platform? I am going to play this soon and may speedrun it in the future.

Also, I don't have a Wii currently at the moment. But I hear it's easier to get JP on Wii than Gamecube?

Yeah gameplay-wise playing the game disc on a GameCube or a Wii is identical. The only way it wouldn't be would be if one was using some banned Wii homebrew software. Otherwise a Wii will always slow itself down to match GameCube clock speeds. When the speedrun.com page was setup it was just decided to only list the game as being on GameCube, since even when it's being played on a Wii it's still the same GC disc. Some, but not all other games also had this same thinking for their leaderboards. /shrug

Using a backwards compatible Wii does have some minor practical advantages though, and that causes them to definitely be more popular among speedrunners of FFCC and most other GameCube games.

For one, there's just more Wiis in the world so they're cheaper to get if you don't already own a console. It also be cheaper/easier to get 480p output out of a Wii instead of 480i which looks a little better and is more compatible with modern displays (though that's a whole other can of worms for FFCC specifically as using 480p causes some weird speedrun-specific issues for certain categories; see here if interested: https://www.speedrun.com/ffcc/guides/0bab9).

Additionally, Wiis tend to have better and more reliable disc drives. This makes them typically load slightly faster and be less prone to disc read errors. However, note that is not necessarily universally true and is purely on a console-by-console basis. Some GameCubes I've seen are faster than some Wiis I've seen.

Lastly, it is indeed much easier and usually cheaper to mod a Wii to disable its region lock, which a lot of us need to do to play the JP version on our USA or PAL consoles. You pretty much just need an SD card and a PC with an SD card reader to mod a Wii. It's a much bigger hassle on GameCube to bypass the region lock. Your only options, as far as I know, are to figure out the least expensive/annoying way possible to boot the Swiss homebrew (while keeping the disc drive intact since that's required to speedrun officially, no SD card loading/etc.) or find a (probably expensive) freeloader or action replay disc that can be used before playing the game since those can also bypass the region lock.

tl;dr: No real difference between GameCube and Wii. Wiis tend to load the game slightly faster on average, but we're talking like 20 seconds or less across an entire run at absolute best. If you want to run glitched categories then using a non-JP GameCube is probably a lot more annoying than a non-JP Wii just because Wiis are very easy softmod to get around the region lock while for GameCubes this is much more annoying (and probably more expensive).

If you do end up getting into the speedrun I definitely recommend joining the discord server just because it's easier to find resources and ask questions in there at the moment! Hope this helped.

Ok, Thanks. Appreciate the help. <3