Brawls

Successful brawling will give you chests that provide you with materials to upgrade your toons. Brawling looks very intimidating at first, but Scopely has added a few things to make it easier for you. 

Some of the players you attack for crates are actually bots. Bot teams are made up of random toons that are usually easier to defeat than player made teams. You can identify a bot team because it has random toons and it won't allow you to add the player to your guild. 

Another way the game makes it easier to open crates is it limits the possibility of attacks on your crates. I haven't figured out how the system works, but after a while of protecting your crates you can be assured that they will be safe for opening when the time expires.