The pivoting is easy. Just run forward, pivot, then while you're turning, smash forward again to run. It's nothing special, just something I like to use to confuse opponents as to where I'm going. If you were talking about the pivot aerials, it's simply jumping out of pivot the frame your character finishes turning around. I had a lot of practice using it with Charizard in PM, and the skill carried over well.
I mean, without a doubt your Shiek is solid. She's definitely one character that can gimp me offstage relatively safely. I'd try ledge dropping an aerial that stays out a long time if you think I'm going to up b aiming for the ledge, as even the luma is in stun while I'm using my recovery.
Your Ike was much better once you stopped going for me offstage every time. Other than that, it's just spacing those aerials. Oh, and if you ever see me about to grab the ledge for a second time without touching the ground first or getting hit, find something to punish it quickly. The lack of invincibility on grabbing it is really a huge deal.