Problem with Star-Spangled is that she's oriented for offense ability-wise but doesn't have the necessary offensive tools to back that up. She's a product of her time.
1. Stats: 88k HP is HUGE for defense. 11k ATK is
passable for offense
2. Ability: All Cerebellas can inflict ARMOR BREAK through BATTLE BUTT so there's nothing unique that she offers
3. Stun: The only thing she offers, but is limited to hits in the air which is fine but not enough. You can do some sort of loop in the corner with her ability, but you'll most likely time-out against tougher defenders
Given her Water element and high HP stat, a rework towards a defensive variant would be the best way to make her viable in the game (although that's boring). I'd like to see her being kept as an offensive Water variant since that's rare, but she'll need a lot of help.
Some ideas:
1. Damage based on HP% (like Brain Freeze but make it better since she's a Diamond)
2. Some form of instant HP% reduction that won't rely on her ATK stat (like Summer Salt's first SA)
I prefer the second idea so perhaps something like this:
SA1: Inflict ARMOR BREAK for 15 seconds when either Fighter breaks a THROW. ARMOR BREAK can stack.
SA2: 25% chance on HIT to inflict STUN for 5 seconds and deal an additional 3% of the opponent's MAX HEALTH if the opponent is suffering ARMOR BREAK and is in the air.
Since she's a Diamond, I thought her abilities can break the rules a bit by allowing ARMOR BREAK to stack. Dunno how difficult that would be to implement, and I suppose it might open some doors to bugs lol. If not, we can always slap an ENRAGE onto her which essentially does the same thing. Maybe the damage boost might be too much, but hey, it's a Diamond!
Another idea is to inflict DEATH MARK instead to synergize with moves like BUTT SLAM and LOCK N' LOAD which works in the air. Doesn't seem to fit the flavor and theme of Star-Spangled though.
Second ability is harder to pull off but once you get the opponent in the corner and STUNNED, you can go D2 > Cerecopter to potentially reduce their health by a significant chunk. Nobody uses Cerecopter so Star-Spangled having that synergy could be a cool niche and new way to play Cerebella.