there's no way to back up the game saves .
I remember when Rocky said this and my heart melted. Backing-up save files are so important, for a lot of reasons...like if your Wii gets corrupted and your files get destroyed. (I know this happened to Rocky already.)
But after so much searching...I found the solution, you can actually back-up MKW and SSBB game saves via hacking.
Although I'm skeptic with trying this (because I'm scared the reverse would happen and the save files get corrupted even more.)
First, you need Twilight Princess and an SD Card. It's something called the Twilight Hack, which you use to activate most hacks made up by hackers. This particular hack will allow you to back-up your save file to an sd and return it to the wii when needed later on.
NOW THIS INVOLVES DELETING YOUR TP SAVE FILE! IF YOU VALUE IT, BACK-IT UP IN YOUR COMPUTER!!!The
hack zip file contains several versions of save games that you will need to choose correctly depending of your version of the Zelda game. The easiest way to check your version is to compare the text string which is on the inner cycle of the data surface with the ones below.
Different Versions
RVL-RZDP-0A-0 JPN rzdp0.bin
RVL-RZDJ-0A-0 JPN rzdj0.bin
RVL-RZDE-0A-0 JPN rzde0.bin
RVL-RZDE-0A-0 USA rzde0.bin
RVL-RZDE-0A-2 USA rzde2.bin
Next, follow these directions:
1. Format your SD card to FAT16 (In Windows it’s called just “FAT”) or with 0.1alpha3b FAT32 if it is not already.
2. If it does not already exist, make a directory called “/private/wii/title/RZDx/” on your SD card; replace “RZDx” with RZDE, RZDP or RZDJ as appropriate. Copy the above file into that directory, renaming it as “data.bin”.
3. Next, take the .elf file (in this case it is either
extractor for backing-up &
installer for putting it back in the wii), and save it in the root directory of your SD card as “boot.elf”.
4. Now, put the SD card into your Wii and turn it on. Go into Wii Options –> Data Management –> Save Data –> Wii.
5. Find your Zelda save, click on it, and click “Erase”, and click Yes.
6. Now, go into SD card, and select the “Twilight Hack” save (the icon says “Wiibrew Loader”). Click copy, and yes. Now, go back out of that menu.
7. Insert Zelda, and run the game. Load file A, and either walk backwards, or talk to the guy that’s standing in front of you. (Rusl, if I'm not mistaken)
8. The code interface will appear, take out your TP game, put in the game that you want to back up its save file.
9. Press the reset button. When it's done, press the power button.
Oh yeah, there's an additional pre-step for the installer:
Copy the game save you want to install to an SD card (directory should be “wiisaves/” and just keep the directory structure created by the Savegame Extractor).
Well, now at least you know you have a back-up for your hardwork.

UPDATE: I JUST DID IT AND IT WORKS!!! WOOHOO! I am now OFFICIALLY happy and secure.
UPDATE: Also, this application cannot be used with the Homebrew channel. You must use this Twilight Hack method. The Homebrew Channel method can be used for other things like Ocarina. Here's how to add homebrew channel:
http://www.smashpower.com/forums/index.php/topic,5954.0.html