Using Kirby's rock attack, (though dealing no damage to him whatsoever) does not work, you still go flying  off the stage with 0%! As stated before high-flying characters would be good against a boss like Tabuu. A strong character would be good too so I suggest Meta Knight with multiple recovery moves and multiple jumps. A character like Yoshi would be considerable due to his high jumping ability as well as Lucas and Ness but not recommended since all three have little recovery after that.