Whenever a new Super Smash Bros. Ultimate character is announced, one of the big questions that then starts being asked is what the accompanying Mii Fighter costumes will be. In the past, the new costumes have been capable of generating just as much excitement/disappointment as the actual fighters. While they can be perceived as a compromise, allowing otherwise impossible characters to join the roster in some way, it's not quite the same as them being their own unique playable fighter, with the likes of Sans from Undertale and Geno from Super Mario RPG being included in this way.
One would think that the newest batch of Mii Fighter costumes would be inspired by Xenoblade Chronicles 2, since that's the game Pyra and Mythra (the new DLC characters) come from. But rather than costumes based on characters like Morag and Zeke, fans can instead purchase four Capcom-themed costumes; three of which are from Monster Hunter.
The Monster Hunter series was already represented in Super Smash Bros. Ultimate with the Rathalos Assist Trophy and boss fight, but the costumes will let players dress up their Miis as the titular hunters themselves. One of them decks out a Mii in the Hunter Equipment, while another is the Rathalos Equipment set. That second one was DLC for the last Smash game as well so it was only a matter of time for it to be reintroduced in Ultimate.
Both of these costumes are for Mii Swordfighter characters, while the last one - a Felyne hat - can be worn by anyone. Sakurai adds that this is to tie in with the upcoming launch of Monster Hunter Rise for the Nintendo Switch. The final costume is instead based on Arthur from Ghosts 'n Goblins, which also received a modernized remake recently.
While this is only speculation, these Monster Hunter costumes could very well mean that the theorized playable Monster Hunter character isn't happening. The lack of the costume's appearance until this point had some fans believing that it meant a Monster Hunter would be one of the DLC characters. But, if that were to be the case, it probably would make more sense to release matching Mii costumes alongside the character.
This could also disprove the concert leak. As a reminder, this leak claimed that a concert would take place after the DLC for Ultimate was complete and contained a track list that seemed to accurately predict Pyra and Mythra's inclusion. That same leak suggested that a Monster Hunter character and Crash Bandicoot would be DLC, but now many believe this has been ruled out entirely thanks to the new Mii costumes.
Super Smash Bros. Ultimate is available for Nintendo Switch.