Nice moveset, but I would change a few things around:
-Standard Special: Missile Barrage [takes place of your Metroid Swarm; and I moved to to Standard]
Missile stack up in DS's arm (like Sheik's Needles). They take quite a while to charge, but are well worth it. They can add up to five in total. When released, they slowly fly towards the closest target from more than one angle (like Samus' missile). Not all are guaranteed to hit, and sometimes they lose target, fly off course, and pick up speed for heavy damage.
[Normal Missile= Small knockback, 3% damage]
[Stray Missile= Medium knockback, 5% chance to stray, 15% damage]
-Down Special: Phazon Comet (lolz, is that better? I don't really know)
(Does everything you said. I love it, not going to change a thing, but I want to add on to it.
) Works like Ganondorf's dB, except it corrupts and meteors instead of spikes. If done in a grounded position, DS pops straight up and slams back down resulting in a large explosion. (The same can be done by landing with it aerially, but the explosion is bigger if done while grounded. And the cooldown time from recovery is longer if grounded.)
{Grounded dB}
[DS= Medium knockback, meteor, 7% damage]
[Explosion= Heavy knockback, 15% damage]
{Aerial dB}
[DS= Medium knockback, meteor, 7% damage]
[Explosion= Medium knockback, 8% damage]
-Up Special: Particle Formation
(Brilliant idea, I'm not touching it. Great job.)
-Side Special: Phazon Beam
A powerful move that takes a while to warm up. Patience and time are required. First, DS collects loose Phazon from the air into her arm-cannon; second, she focuses it into ammunition; finally, she unleashes a beam of Phazon that deals heavy damage and pushes anyone in contact with it backwards (as long as they are in contact with the beam.) This move can be shield-cancelled due to long warm up time. Initial blast is long but receeds quickly over time. Once the beam is fired it can't be shield-cancelled.
[Collecting Phazon Particles= light knockback, 1% damage]
[Phazon Beam= No knockback but a constant and fast push as long as contact with the beam is kept, 8% damage per second while in the beam]
Hey, that was really fun. Thanks for the ideas Aphotik!