... What's Spectrum's power again? Making rainbows doesn't seem like something to get her on the team. Also, did flourish's cutie mark change when she got her power? This is such a great story and it irks me when I don't get things like this.
Spectrum is stronger and faster then other ponies. Flourish's cutie-mark did indeed change when she gained her power, altering from a simple rapier mark to a rapier with a pink cloud backing it.