Since MLB 2K8 for the Wii lacks online play, that most likely means 2K Sports will not produce any roster updates for the game. However, since the Wii supports saving to SD cards, I can make updates and share them with you guys.
I will make numerous throughout the course of the 2008 season and post them here for everybody. To help you use these saves, I have links explaining how to use them, as well as how to contact me.
This update changes all fake player names to the proper names. For example Joe Young is changed to Barry Bonds. A number of other minor updates are made as well. See README (also contained in download) for further details. No transactions are contained in this download, they will be in the next update.
Unfortunately, there is one major downside to using updates. You cannot use your already created franchise, season, profile, etc. with the created roster saves posted on this site. What I would suggest is you back up any MLB 2K8 data on your Wii right now on your computer, then copy the roster file onto your Wii. This way you can switch back and forth between the saves. If you dont mind creating a new franchise/season then you are fine.
Downloading
When you download an update, you will get a folder called RK8E. Now, on your desktop create a folder called private, inside make a folder called wii, and inside that make a folder called title. Paste the RK8E folder inside the title folder.
Backing Up Data (only if you already have MLB 2K8 save data, otherwise go to next step)
Make sure you back up your original data. This requires an SD card.
They can be reasonably cheap and purchased at any electronic store. They are also used by most digital cameras. Insert the card into your Wii. Go to Wii options (button saying Wii with circle around it). Then Data Management, then Save Data and finally Wii. Find your MLB 2K8 save data, insert your SD card and copy the data to your SD card (click on save data and select copy). Then insert the SD card into your computers SD drive and copy the private folder to a safe location on your computer.
Saving to SD Card
With the card inserted in your SD drive, copy the private folder with the downloaded file in it (not the one you just backed up) onto the SD card. If you already have game data on the card and have backed up any MLB 2K8 data, simply drag the RK8E folder into the title folder on the card (overwrite the old folder if it exists but ONLY IF YOU HAVE BACKED IT UP).
As you noticed, I have multiple warnings about backing up data. They are probably annoying you and they will stop now. However, I will not be held responsible if you dont read the warnings or dont follow the steps properly and your original data is erased.
Putting New Save on Wii
Now insert the SD card into your Wii, browse back to the save data and delete the MLB 2K8 data on the wii system memory. This contains all of your already existing data, but if you backed it up you can copy it to an SD card abd use it again. Then click on the SD Card tab, find the MLB 2K8 save and copy it to the Wii system memory.
Now run the game and you will have the roster update!