No. Cloud does not appear in Brawl.
No.
You can't he's not a playable character and Cloud is'nt either.
What character?
No, Pichu is not a playable character in Super Smash Bros Brawl
You cant.
No, but Snake and Sonic are.
No, Jack Skellington is not a playable character in Super Smash Bros. Brawl.
No. Mewtwo is not in Super Smash Bros. Brawl. If you want a character that resembles Mewtwo, then that would be Lucario. Though Mewtwo is in Super Smash Bros. Melee.I'm afraid not. And, no, there is no hack or secret strategy to get it.
Shadow is not a character in Super Smash Bros Brawl, unfortunately.
Pichu is not a playable character in Super Smash Bros. Brawl.
Midna is not a playable character in Super Smash Bros Brawl
Dark super Sonic is not a character in Super Smash Bros Brawl.