With exception of Kim Kaphwan, Raiden and Hwa Jai (three characters who debutes in the Fatal Fury series; Kim debuts in the second game, Raiden and Hwa Jai in the first game of the series), the other members on this team are exclusively created for the KOF series.
This team also doesn't appear in the initial cast of The King of Fighters XV, due to the fact that Kim were training in the mountains with his master Gang-il. This is explained in the Secret Agents Team's Story and in Luong's interview with Clemence Bellamy, and is also seen in the ending of the team in the previous game. The fifteenth entry is the first game in 28 years where it doesn't feature Kim in the initial roster.
Kim appears in KOF XV as a DLC character in the Season 2 of the game.
The other probable main reason of the character's non-inclusion in KOF XV's initial roster is due to the recent death of the real Kim Kaphwan, founder of Viccom, a Korean company that for many years licensed SNK's games, and that inspired the ficcional character.
With exception of the variant formed by Jhun, Lin and Shingo, the other formation of this team is canonical.
All the members of the mainline variants of this team practices Taekwondo (and its variants).
In the alternative formations, Lin practices Ninjustu, Shingo practices an alternative version of Kusanagi clan'sfighting style and Xanadu has no fighting style.