When Smash comes out, it will be a complete game. The original reason, that DLCs cost money is because it requires money to make a DLC. And I hope they do create a character DLC as an add-on later on. The Smash community would appreciate a new character or two when they hype settles down.
Everybody here is discussing about characters while I'm here just waiting what stages will come in...
And as for DLC, any staff still developing DLC requires pay. If certain DLC takes a notable amount of time or effort, then it most certainly won't be released as free.
I do, however, see Pokemon having DLC in the future. Soon. Soon.
*plays an online match*
"Oh hey, this guy's playing as Batman. I wanna try."
Smash 4: "**** you, where's my money?!"