Rathalos

A Rathalos is a type of flying from the  series.

Super Smash Bros. for Nintendo 3DS / Super Smash Bros. for Wii U
Super Smash Bros. for Nintendo 3DS and Super Smash Bros. for Wii U feature a downloadable outfit and headgear based on the Rathalos for the Mii Fighter. The outfit is titled Rathalos Mail, and the headgear is called Rathalos Helm. It was released for Wave 4 of the Mii costumes DLC.

Super Smash Bros. Ultimate
In Super Smash Bros. Ultimate, Rathalos is introduced as an Assist Trophy and as a boss in both Classic Mode and the World of Light. Rathalos is one of the few third-party Assist Trophies without any playable fighters from their home series, with the others being Akira, Bomberman, and Shovel Knight.

As an Assist Trophy, Rathalos can strike the opponent with his claws or breathe fire onto the stage. When he roars, nearby fighters may be stunned. In the boss fight for Rathalos, the player fights him on a flat plains stage resembling the Ancestral Steppe from the Monster Hunter series. He is fought in the final round in the Classic Mode routes for Yoshi, Marth, Duck Hunt, and Piranha Plant. He is also fought in the Classic Mode route for Bowser, Hero, and Sephiroth, albeit before the final round (with Mario and Metal Mario for the final battle for Bowser, and with Robin and a giant Charizard for the final battle for Hero, while Sephiroth's route is akin to a boss rush, with Rathalos as the first opponent). During the boss fight, Rathalos can use all of its attacks from his Assist Trophy form (with its claws also dealing poison damage), while also being able to ram the player, swing its tail at them, and fly into them from the background. At certain points, Rathalos may retreat to the background and unleash massive fireballs which will carpet the ground on fire for a few seconds. Although it can be attacked anywhere at any moment when it is faced head on, the most effective method to fight Rathalos is by immobilizing it with items like Pitfalls and Deku Nuts, which can appear either randomly or by striking its tail.

The Rathalos-based outfit for the Mii Swordfighter is also available as downloadable content, having been released in the 9th wave of Mii costumes alongside Pyra and Mythra.