Pencil Hoof

But then if you only look at what a character does, you'll never gonna be able to completely read into the plot or characters...

WellI watched the whole episode again, it left a lot of questions... At first, it seemed like she couldn't really transform into anything but small objects, or possess objects in general. Then her power jumps when she suddenly turns into The Shadow Bolts. At first I thought that, was it, I guess she can transform, but as I thought about it more, I realized, that this was most likely some sort of illusion a holograph or that sort of thing. Mainly because, if she could transform into some sort of monster, especially something as powerful as Chrysalis, why wouldn't she have done it in the first place? I realized the most likely answer, is because she wouldn't be able to actually DO anything. Why didn't The Shadow Bolts just take Rainbow Dash out? She was by herself, no one else could reach except Fluttershy, (who isn't the strongest fighter (but still is best pony XD )) and they were in the middle of the EVERGREEN FOREST. There must have been plenty of places to hide Rainbow Dash if she didn't want to kill her. And if she'd hidden her and, as you suggested, she can transform her shape, she could even have turned into Rainbow Dash her self. That way, she would have been able to destroy the Original Elements of Harmony, and when Twilight tried to create the Elements in her friends, one would have been missing.Also, as we can see when she charges head on at Twilight, she obviously was ready to take one of the ponies on directly in a battle of Physical Strength. So the only answer I could come up with, once again, is, because Shadow Bolts were simply a conjuring, she COULDN'T. In other words, she can't change, she doesn't have the ability to turn into another pony, or animal. If this theory is to work it's gonna have to be the other way around. Is Chrysalis Princess Luna?

If Cadence is Celestia's niece, she is either Luna's daughter (which seems unlikely, because Luna and her didn't even talk in the episode) or, they have another sibling. If they have another sibling, what was their power? Were they there at the beginning of time as well? And if not, then how did they appear? How come they've never mentioned him/her before? So many questions...

Well I think the main problem with this theory is that it's very unlikely Luna has the ability to change forms. So her changing into a changeling is one thing, because it kind of looks like her, but into Princess Cadence... that seems iffy :/ Maybe it's the other way around? Maybe the changeling queen also disguised herself as Luna?