A 4v4 splatoon style pvp mode could be fun and unique enough to warrant its own mode. Splatoon is a fps where your weapons also paint the map with your teams color and you run faster in your own color but slower on unpainted areas or on the other teams paint. This could possibly extend to teleporting farther on your own paint than other colors.
To get away from just another team death match or ctf or moba or last man standing, this mode could have the two iconic splatoon modes- king of the hill (maintain a certain spot your teams color for 2 mins) or a 2 min battle to ink the whole map and whoever's team has a higher % of inked territory wins. These would make for quick pop in matches.
The aesthetic could be like a art classroom with eisles and colored crayons/paint etc.