We know that Nintendo has stated that they have plans to release DLCs for Super Smash Bros. Ultimate in the future. These DLCs are expected to contain new characters that will be added to the roster, new stages, and new music. In what order they will be released remains is anyone’s guess, but it seems that a recent datamine might have revealed some information.
In a datamine by @jam1gamer, it has revealed some character codenames that are expected to be in an upcoming DLC. These codenames cleverly do not tell us who these characters are, but some have speculated who they might be referring to as these codenames do seem to provide some hints.
For example one of the codenames is “jack” which some have taken to indicate Joker from Persona 5 with Atlus mascot Jack Frost. Then there is also “Packu” which could be referencing the Japanese name for the Piranha Plant “Pakkun Flower”. Then there is also “Brave” which some think could be referencing Dragon Quest where the hero is referred to as “勇者”, but when shortened to “勇” is the kanji for “Brave”.
These do seem like quite educated guesses but whether or not they are accurate remains to be seen. However there are rumored plans for a Nintendo Direct presentation next week, and if it does happen we suppose details about the DLC could be revealed then.