Your Wii needs to be hacked, and the only games you'll be able to play via SD card is anything from the online store, so VC and WiiWare.
Play stuff via USB. A lot easier than SD. And you will be able to store a lot more data on them if you buy a portable harddrive for your Wii.
yes you can, but your wii needs to be modded.(which only requires any 2gb sd card) i have a hacked wii and i was able to back up super paper mario and new super mario bros and play them from my SD card since they are the smallest wii games in size. you can also use a usb. you don't need those expensive hard drives. most wii games are 4gbs so it's pointless. just buy an 8gb usb from radio shack.
It isn't pointless. Do you really want to have to delete and copy a game to play on the Wii each time you download an ISO? Sure, an 8GB USB is fine if you're planning to only play one game. But if one wants to play multiple ones, them you get a HDD.
ehdds are not that expensive, and if you keep erasing and reloading stuff on a usb you'll wear it out. you could do that all day every day for decades with an ehdd and it won't wear out.