OK, TimB managed to kick my own O.C. into gear, so, here's a list, best as I can remember, of Peter's current skill set.
Power Mimicry (his native power) Flight (from Nathan Petrelli) Prophecy/Paint-the-future (from Isaac Mendez) Space/Time Manipulation (from Hiro Nakamura) Regeneration (from Claire Bennet) Sylar's power set (see below) Telepathy (from Matt Parkman) Invisibility (from 'Claude'

Radiation Generation (from Ted Sprague) Super-strength (from Niki Sanders) Phasing[intangibility] (from D.L. Hawkins) Electrodirection (from 'Elle'
Since D.L. was beside Molly Walker and Micah Sanders at the time, Peter should also have Molly's teleolocation and Micah's technopathy, although he hasn't used them.
Peter also may or may not have Eden McCain's Persuasion
Sylar's power set (for TimB, Sylar, aka Gabriel Gray, is the bad guy, who could acquire powers by killing the person, cutting open their heads, and using his native power to understand how the person's power works)
Telekinesis (from the late Brian Davis) Cryokinesis (unknown, possibly the late James Walker) Eidetic Memory (from tl Charli Andrews) Liquification [can make solid objects liquefy] (from tl Zane Taylor) Auropathy [super-hearing] (from tl Dale Smither) Radiation Generation (from tl Ted Sprague)
He may also have, but not be able to use Candice Wilmer's Illusion power, but if he does have it, Peter doesn't, since he would have got it after the Kirby Plaze fight.
He probably had other powers we haven't been shown, since he certainly cut at least three heads open that we don't have a power attributed to.
Other than Candice's power, Peter should have all the powers Sylar had, including his native power to 'understand how things work'.
OK, what powers have I missed?