Have you ever seen America's Psychic Challenge? How do you think the special abilities would develop upon turning for people who are more or less do everything like see through objects, find people or things, communicate with spirits, see past, present, and future events, see auras, tell if someone's lying, heal, communicate with spirits etc. How powerful would they be and what would the Volturi do about them?
I have not seen America’s Psychic Challenge, unfortunately, but I’m broadly familiar with various psychic tests. Hopefully this lets me answer your question properly; give me a shout if I’ve missed or misrepresented something!
I’m intrigued by the idea of the Volturi initially turning notable psychics and finding themselves with all kinds of clever charlatans on their hands. Cold readers who “spoke with the dead” became vampires who noticed body language and were good at statistics. Clairvoyants were just hyper-observant, and in their vampiric form could piece together tiny clues, Sherlock Holmes-style. Alleged healers became mood manipulators or low-key illusionists. In short, the Volturi quickly realized that just about everyone who claims to have extra-sensory powers for profit is lying. (If, conversely, their power terrifies them and they’re ostracized, they’re much more likely to be the genuine article.)
So, if a person who excelled at all kinds of modern psychic tests became a vampire, they’d just… be really sneaky, or very good at reality television. The skills underpinning these challenges are completely different; I can’t see how one person– even in the Twilight universe– could possibly possess them all.
But, for the sake of argument, if a person with the power to pass every psychic test existed and got turned into a vampire, I imagine that they would be driven mad by their enhanced and overwhelming abilities long before the Volturi got to them. Seeing the past, present, and future and reading minds (in an admittedly limited way) has done a number on Alice and Edward and even Aro. And that’s not even factoring in the x-ray vision and the communication with the dead and the heightened empathy and the auras and so on. No way would this vampire be anywhere near stable or controlled. I’m not even convinced they could feed themselves; wouldn’t the souls of their inevitable victims torment them from the great beyond?