Here are her attacks, and how to dodge/avoid them:
Attack 1: Jump and Slam
Eclipse will pause for a while after hopping around the stage, and then jump up high into the air. Impacts once she lands on the ground, dealing damage. After landing, she continues to hop around the stage. This attack can bounce from the edge of screen. To avoid it, stand under the peak of her jump, or just stand as far away from her as possible.
Attack 2 (At half health): Cotton Shower
Eclipse will stop hopping around the stage for a while, scatters a bunch of cotton around the stage, and continues hopping around. It's not known what the cotton do to the player except to just stick onto them. This attack doesn't deal any damage, so there's no need to worry about it.
Attack 3 (At half health): Charge Attack
Eclipse will stop hopping around again. She hops on the spot a few times and charges forward. Impacts when she hits the player, dealing damage. This attack bounces from the edge of screen. To dodge it, time yourself and jump over her when she's about to hit you.