What's the use of emblems?

Aside from collecting, what are the other uses of emblems? Do I get items if I complete a set of these?

 

I have them all, but I didnt get anything. I dont know if they are any use.

 

I think they may be for the wallpapers, the number of wallpapers compared to the emblems seems pretty close...do you have all the wallpapers?

 

Im missing 14

 

if u havnt done challenge training for every character yet those r the 14 that you r missing except lion somhow he doesnt get one..? buh the challenge holds the 14 that ur missing, but im not sure what emblems r connected to

 

I got all the players and emblems but they only seem to get your overall rating up.And how are you meant to do the challenges!?! They are well hard!

P.S Does Lion Get something for doing the challanges in the first place?