Chrom

Chrom is the main protagonist of Fire Emblem Awakening. He is the father of Lucina, a distant descendant of Marth, the best friend of Robin, and the prince of Ylisse. He made his playable debut in Ultimate.

Super Smash Bros. for Nintendo 3DS / Wii U
Chrom appears in Robin's Final Smash as a supporting character. In the Final Smash, he dashes forward towards the opponent and catches them. If this happens successfully, Robin and Chrom unleash a powerful series of attacks on the opponent before dealing a final blast down on the victims, dealing high damage and incredible knockback.

Although Chrom is not a playable fighter, Masahiro Sakurai stated that Chrom was commonly considered to be a playable character following the successful release of Fire Emblem Awakening, but Robin was chosen instead as Sakurai felt that Chrom was too similar to Marth and Ike and he would not be an original enough character. Chrom is still a costume for Mii Fighters instead, and there is a QR Code for players who wish to access the costume themselves.

Super Smash Bros. Ultimate
Chrom debuts in Super Smash Bros. Ultimate as a playable character. He was officially announced on August 8, 2018 along with King K. Rool. He can be unlocked by playing World of Light, taking part in VS. Mode for 9 hours and 40 minutes and having 58 other characters unlocked, or by completing Classic Mode with Yoshi at least 7 times and having 6 other characters unlocked.

Trivia

 * Chrom is the only Fire Emblem character to appear as part of a character's moveset prior to his playable debut.