Rathalos
A Rathalos is a type of flying wyvern, from the Monster Hunter series of games produced by Capcom. A Rathalos appears in Super Smash Bros. Ultimate, as an Assist Trophy and as a boss in both the Classic Mode and the Adventure Mode: World of Light.
As an Assist Trophy, he can strike the opponent with its 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 as the final boss in the Classic Modes for Yoshi, Marth, and Duck Hunt.
In addition, Super Smash Bros. for Nintendo 3DS / Wii U features 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.
Gallery
Promotional drawing of Mario fighting Rathalos, posted in a Tweet by an official Capcom account