Its not stated in the rules but if you have changed your name and you are joined in a tournament on the forums, please post in the respected thread (or pm the tournament host) to prevent some confusion that will occur.
You might wanna change this due to DE changing his username.
Shining Raikou said:
You are not allowed to use a username that someone else previously used. (So I can't name myself dragonexpert even if I think I am the #1 authority on dragon-related things)
I would like to change my username to Argetlam, please, spelled exactly like that with a capital A. ~done. Please edit your signature with your former username.~King Arceus