if you are using USBLoaderGX, you don't even need to patch your ISO to join private servers.
there's an option to do the patch on the fly in the game settings.
USBLoaderGX is doing it at launch and works for all compatible games.
Only MarioKart requires an additional patch if you want the "full changes", which includes :
- new displayed text message (instead of "nintendo it says wimmfi ... not very important to play the game, right?),
- patches the player searching algorithm to remove all restrictions (you could be a noob and play with a pro)
I personally prefer not patching these, and only patch the server access using the loader's option.