StaticShin27
Brave Sound~
Heisei series have enough of problem with adding Riders just for the sake of adding Riders. Diend is a fair bit of a tack-on himself when the entire the premise already provides a vast array of Kamen Riders.
aside from just the sake of doing it, also note that for toy sales they either do one of the following:
1-3 riders: many forms for the main rider
3+ riders: limited forms to the main rider, but consistently adding on moar riders
