That component is C602, and it's an 0402 1uF ceramic cap. The Wii will probably work fine without it. There's plenty of decoupling capacitance nearby on the 3.3V rail already.
If you want to be cautious and replace it, you can steal a 0.1uF cap from elsewhere on the motherboard. Maybe C122 or C140 from the P4 Gamecube controller port. (Not the same value, but it can't hurt.)
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Or you can
buy a new 1uF cap. Either way you will have to do some precise soldering. This is more like soldering practice than resuscitating a bricked mobo. It should work fine without the cap.