Mii Fighter Costumes are coming to Super Smash Bros. Ultimate in 2019 according to the official Nintendo website Super Smash Bros. Ultimate DLC page. The page was updated recently and it shows both the price and TBD release date for the costumes but it states the date of 2019.
According to the DLC information, each Mii Fighter Costume will include 1 costume and will cost $0.75 each. This might mean that more Mii Fighter variations will be added in the game in the future or they could be simple skins for the already added variations to the game.
Apart from these new additions, the page lists the normal DLC information of Super Smash Bros. Ultimate which include the Fighters Pass and Individual Challenger Pass. Each new fighter added to the game as DLC will come with its own unique stage and music.
Players can either purchase the single fighters as they come out for $5.99 each or purchase the one time Fighters Pass and receive all future DLC for $24.99. This will include 5 DLC fighters each with their own special stages and music tracks with a bonus Xenoblade 2 Rex Mii Fighter Costume.
Apart from this, all players who purchase or register their game before January 31, 2019 will also get Piranha Plant as a free DLC otherwise players will need to pay for it if they purchase the game after January 31, 2019.
The developers of Super Smash Bros. Ultimate have already finalized all DLC characters but they are not yet revealed for the general public and they will be gradually revealed later in 2019. Seems like 2019 is going to be a good year for Super Smash Bros. Ultimate.
If you want to check the official DLC page yourself, head right here. If you are still looking to purchase Super Smash Bros. Ultimate, purchase the game before January 31, 2018 and you will get Piranha Plant as a free fighter. We have added purchase links for both Digital and Physical version below.
Super Smash Bros. Ultimate is now out for Nintendo Switch exclusively.