Red is for the games you want to play. Currently I only have Wii U requests filtered 'cause I suck at 3DS :3
Orange is where they live. Red means pretty far away while the brighter the colour, closer they are. Green is the closest
Yellow is the peps asking for matches. Just click on the logo to automatically challenge them
Green is the chat. It's kinda useless and you don't have to use it
Dark blue is the rank. You have to fight 8 ranked matches first before you can get a rank
Light blue is all the cool stuff where you can choos your mains, themes, and look at ranks
Purple is the system ( I guess). Friendlies doesn't count to your records while ranked does. Featured Streams show which streams are there for you
Gray is the people