Mii Channel

A Mii (ミー Mī) is a digital avatar used in the Nintendo Wii gaming console. They allow users to capture a likeness (or a caricature) of themselves and others. After creating one using the Wii's Mii Channel, they can be used as characters in Mii-oriented games such as Wii Sports, Wii Sports Resort, Wii Fit, Wii Fit Plus, Wii Play, Mario & Sonic at the Olympic Games, Mario Kart Wii and other titles.

Wii consoles can store up to 100 Miis, up to 10 of which can be favorites. The Wii Remote itself can hold up to 10 Miis on its internal memory, which can later be transferred to another Wii console. However, they can only be edited on the console on which they were created. In addition, Miis can also be exchanged via the WiiConnect24 service, whereby allowing a player's Miis to "mingle" will enable such Miis to appear on other people's Wii consoles.

Transfer Miis
Transferring Miis works only with real Wii Remotes. The read/write will vary depending of the bluetooth adapter and stack used, varying between 5 sec to 1 minute sometimes.

Gameplay Videos
Here are some videos to compare the compatibility. (Left is oldest version and right is newest version)