Many Wii games are on .WBFS format, but you can't transfer these games to your WII, if the games are not in ISO format.
To convert WBFS to ISO, is very simple. First download the Wii Backup Manager and choose the file you want to run (32 or64bit). Then select "Files", "Add" and choose the file you have your game.
Your game will appear in Wii Backup Manager. Select it and then check "Tranfer" and "Iso".
You will be asked where to save the final iso and the conversion will begin. Now you can move the .iso to any USB stick or HDD.