Metaknight from the Kirby universe has been confirmed for Super Smash Bros. 4 . This has not been sitting well with some professional Smash Bros. players. Metaknight was so broken that he was banned from competitive tournament play. He singlehandedly unbalanced the whole meta (get it) game, and he is one reason why a lot of tournament grade Smash players stick with Melee .
That being said Sakurai has said a lot of his problems have been addressed. For example, Metaknights Up+B shuttle loop has lost the glide at the end, making it a little harder for him to recover, and making it harder for him to attack out of it as well. However, he does rise into a “large loop” and now the loop hits twice.
We will have to wait for the official release to see if this beast of a character is still broken.
Source: Miiverse