Every couple of months somebody brings of Palpy casting Force Storms as proof of his uber-ness. Hello, he cast said force storms from Byss, where he had been siphoning the life energies of several billion people for like 9 years. That was not a 'stock' Palpy just opening up a can of whoop-ass on the spur of the moment. We have no idea the level of preparation necessary to accomplish such a feat, or the time frame required.
Remember Exar Kun used huge freaking temple to wield the energies he did, The dark lords of Korriban used huge focusing obelisks, and crystals...ugh...how new age
That said given that Byss hosted the Emperor's dark side citadel, doesn't seem likely that he wasn't casting those storms on his own.
Oh, and Kyp has never been shown to be stronger than Luke; he just thinks he is. In Jedi search, Luke had no Idea what the device he scanned Kyp with actually worked. As I recall it showed some dark blotch on his 'aura'
Remember Kyp already was skirting the dark side; which was probable what the readings meant. Think about in if your one of the Emperor's Dark side Inquisitors, you could careless how powerful a given Jedi is (the most powerful master are already dead), but you would need to know how susceptible a given Jedi was to turning to the dark side.
Now the real question is where does Kyle fit into the scale.
Oh yeah. I don't think Leia is even remotely as powerful as Luke.
"The enemy outnumbers us a paltry three to one. Good odds for any Greek...."
"Spartans. Ready your breakfast and eat hearty--For tonight we dine in hell!" ~ King Leonidas of Sparta.