I've seen similar concepts in other fighting games, so it would have been kind of cool if she had an Ordinance mechanic. Imagine if she had a Shulk esque neutral special where she could decide abnormal rules for the match. An ordinance that declares her opponents smash attacks to be slightly weaker, or an ordinance to give her a slight damage buffs below a certain damage threshold, or maybe an ordinance that allows her to pull a random item out of a pool (to ensure there's nothing too crazy that could dramatically and unequivocally change a match.). Although Shulk doesn't just get straight buffs either, does he? His monado arts have a cost to counteract his buffs. Something like that could be cool. Isabelle uses ordinances to change the rules of an entire match, at increased risk to herself. Maybe have ordinances like putting an extra 30 seconds on the matches timer, but at a permanent knockback buff to an opponent for the remainder of the match, and she can only use the time increase every minute. Or maybe an ordinance like Bayonetta's final smash, where she must reach a certain damage percent on an opponent to drop even more damage on them, or she takes the damage she dealt herself if she fails to get her opponent above a certain percent.
Obviously the idea could be refined, and maybe something like that would be a bit too complicated for most casual smash players.