I'm from the PAL region, so I can help. :-)
I've lots of Wii games, both discs and WiiWare/Virtual Console, and never once have I seen a game that runs in 576p. It's 576i, 480i or 480p.
Normal disc games usually runs in 480p.
Nintendo GameCube discs runs in 480i (if you select 60Hz mode).
VC games runs in 576i, unless they're Hanabi Festival games which usually runs in 480i or sometimes even 480p.
But 576p? Never.