The Infrared mode of the C Gear will permit player to do quick battle and trading. About 'quick battle' I don't know a thing; as for 'quick trading', it appears that infrared will allow players to trade directly from their boxes and also it will provide exchange of Friend code between players.
Another part of the infrared mode of the C Gear will be called the Feeling Check. It will 'check' the players compatibility. One of the minigames showed to us is a game where two people have to keep the same rhythm/pace/rate or whatever may be the word.
By the end of the minigame, it will check your result and give you a percentage. Higher is the percentage, higher your rank will be and better will be your reward; because, yes, you and your partner will get a reward, depending on your result.
So what's the use of the infrared ?
Battle, trading and items from minigame(s).
The C-Gear's Infrared menu.