Well in suite case , ellen was totally cast aside to make place for "muse" despite the fact that muse was around since the start ( but didn't do much except 4 eps ).
Muse should have joined forces And then BEAT should have came.
They didn't have much time to expand on them.
But it's even weird since , to this day the best
is still michiru & kaoru from splash star that didn't had this problem at all since they took enough step to make them interract with the rest of the cast at various levels ( enough ) so that you do feel the gap.
That and the fact that they were kicking ass every time tey were on screen.
In fresh setsuna did profit from the void left to be the focus. Ellen did such a 180 that they needed even more chara develloppement to fix this.
In "gogo" it was just impossible to add more characters in a same show without going for an overkill. ( 6 precure in totally the limit that a regular show can handle )