These characters are not truly released yet. On Dec. 12th (I believe that's the date) we'll be able to see them in full action. I was able to see about 5 videos of Nu-13 (not counting this trailer).
Nu-13Not much has changed but the old Nu is back. And Lamda is back as well. She didn't get a huge change just 1 new move. A mode switch. When Nu activates this move most of her specail moves act more like Lamda's specials back in CS. So really you're getting 2 characters in 1. It'll be clever to see where this goes in terms of Nu combos. Players haven't really utilized this new move of hers yet and have pretty much stuck to the old Nu.
All I know is that her Astral animation has changed. She has a new air normal from the looks of things. It also seems that her j.5C can be used as a crossup now. She has a new special that seems more like some sort of pursuit attack where she jumps in the air and does a fancy slash. What makes this a great move is that you can continue your combo and its pretty low to the ground. Honestly an easy 2000 - 3000+ damage there. Mu still has the same issue with one of her Distortion drives and that's trying to combo into it off her 6C. But that's generally a habit that's hard to break. So has she changed much? Not really. Still dangerous to fight against however.
With a guage simaller to Hakumen's she's able to execute certain moves. Mainly she she's known to teleport right in front of or behind her opponent. She's pretty so closing the distance should be no problem. I haven't really seen what exactly she's capable of except for some Trans-AM loop (She actually says Trans-AM)