You unlock every character by either playing through the SSE entirely and finding all of the hidden doors containing unlockable characters or you complete the tasks required for each character to be unlocked normally.
If you're thinking of the Sonic Riders character, you cannot unlock him in Brawl.
krystal is not a playable character in brawl
Dr mario is not an unlockable character in brawl.
Not a character.
Master hand is not a playable character in brawl.
He is not a playable character. you can only unlock a trophey of him
Depending on how you unlock them, possibly.
he is not a character in this game
As a playable character, no.
if you mean by: can you unlock any more secret caracters in brawl? then i dont think so.
Giratina is not a character.
To unlock the assit trophy of Shadow you unlock Sonic. You can not use Shadow as a playable character.