CoolSmash dlc is easy to obtain by using codes that unlock the dlc. All the dlc comes in smash updates. So all u need is codes to unlock dlc. It is possible and no, not only devs can do it. Check the cheats codes thread here in these forums for the codes u need and how to run them.
If u missed itWheres the code? Theres only 1.07 for Smash Bros. I looked in here https://gbatemp.net/threads/post-your-wiiu-cheat-codes-here.395443/
If u missed it
There is 1.1 which can unlock mewtwo. Roy. Lucas. And ryu
Its for pal but it may work on u.s.
The codes obviously need to be updated.
I do know cloud is id 38. And bayo may be 39.