Meta Knight

Meta Knight is one of the main heroes of New Super Mario Bros. Z and is both Kirby's polar opposite rival and mentor. Meta Knight also becomes close friends with Shadow throughout the series, into which Sonic even says, "Of course these guys can tolerate each other." He is a master swordsman and once owned the Battleship Halberd, but it was destroyed by Marx along with the rest of Popstar.

Pre-Mecha Sonic Saga
Before the events of the Mecha Sonic Saga, Marx sent Kirby to find Galactic Nova in order to stop the Sun and Moon from fighting. Kirby realized too late that Marx sent him to Nova so he can make a wish for himself: to destroy the world of Popstar. Marx knocked kirby away, though was recovered by Meta Knight. King Dedede attempted to confront Marx, but was proven to be no match for the crazed jester and kills him. meta Knight and Kirby attempted to defeat Marx, but Marx explained that it was too late to save Popstar and had other plans and teleported to the Mushroom kingdom. Marx managed to escape and slipped through a portal he opened, only to be chased by the two warriors.

Mecha Sonic Saga
Meta Knight, along with Kirby arrived in the Mushroom Kingdom after the destruction of Popstar. As Bowser (in his Metal powerup) was about to finish off Mario, a capsule fell on top of him, causing his metal coverings to get cracked, putting Bowser back to normal. As Kamek threatened to turn Peach into a Fiery Drumstick, Kirby and Meta Knight rammed into him quickly, knocking the Magikoopa away.