There are also some Wii games that can be played with the GC controller. SSBB for example, most people (that played SSBM mostly) even prefer it. I never owned a GC but I have 2 (3 but 1 isn't working very well) GC controllers. I did play SSBM a lot though. Sonic Unleashed also supports the GC controller (I've played it that way).
FE:RD also supports it , but the controls are simple so I just played it with the wiimote (+ its wireless).