Picking Favourites is as Easy as 1, 2, 3!
Simply add 3 qualifying games to your Favourites List. (Hint: remove all the current games saved in your list to speed up the bonus challenge.)
Here is how the add to favourites list icon looks:
Team Brains: Match Wits with Kikos
Send a score of 100 in Kiko Match II (guide).
Team Brawn: Need... More... Usukis!!!
Send a score of 500 in Usuki Frenzy (guide).