The underscore ( _ ) is one of the most used and important symbol in battler tag. It used mainly to differentiate between a name and clan. Removing this from the game has resulted in many clans choosing x as an alternative. This is not always applicable since it may mix with the name (eg: MaxxBush).

The removal of special characters have manly been the profanity issues and having to copy paste which is not very easy for the developer, but the underscore is very common and profanity issues wouldn't be very common.

So futureplay please listen to the community and bring back the underscore back!