To unlock Metal Mario, go into N64 Mode and go to 1P Mode and select Mario. Set it to Very Hard and one life. Then beat the game without a continue. Then exit and you will face Metal Mario. Beat him and he's yours!
To unlock Fighting Polygon Team, go into N64 Mode and go to 1P Mode. Beat the game with all the characters on Very Hard with one life and no continues. Then exit and you will face Fighting Polygon Team. Beat them and they're yours!
To unlock Master Hand (N64), go into N64 Mode and unlock everything. Then exit and beat Classic Mode with Fighting Polygon Team. Then beat the N64 version of Master Hand and he's yours!
To unlock Master Hand (Melee), first unlock Melee Mode (to unlock, beat SSE on all difficulties 100 times) then go to Melee Mode and beat everything and unlock everything. Then exit and you will face the Melee version of Master Hand. Beat him and he's yours!
To unlock Crazy Hand (Melee), go to Classic Mode and beat it with the Master Hand (Melee). Then you will unlock the Melee version of Crazy Hand!
To unlock Crazy Hand (Brawl), beat Classic Mode with Master Hand (Brawl). Then you will unlock the Brawl version of Crazy Hand!
To unlock Male Wireframe, beat SSE 300 times on all difficulties. Then beat him and he's yours!
To unlock Giga Bowser (Melee), go to Melee Mode and beat Event Match 51 with Bowser 10 times. Then exit and you will unlock the Melee version of Giga Bowser!
To unlock Sandbag (Melee), go to Melee Mode and get over at least 1300 feet in Home Run Contest with the 25 characters. Then exit and you will unlock the Melee version of Sandbag!
To unlock Sandbag (Brawl), get over at least 1300 feet with the 35 characters in Home Run Contest. Then you will unlock the Brawl version of Sandbag!
To unlock Shadow Link, beat Classic Mode on Intense with Link's Shadow Link costume. Then beat Shadow Link and he's yours!
To unlock Female Wireframe, beat SSE 400 times on all difficulties. Then beat her and she's yours!
To unlock Red Alloy, defeat exactly 20 alloys on Cruel Brawl. Then beat Red Alloy and he's yours!
To unlock Blue Alloy, beat Classic Mode with Red Alloy. Then beat Blue Alloy and he's yours!
To unlock Yellow Alloy, beat Classic Mode with Blue Alloy. Then beat Yellow Alloy and he's yours!
To unlock Green Alloy, beat Classic Mode with Yellow Alloy. Then beat Green Alloy and he's yours!