Don't forget that Sylar was designated 'Patient Zero' so even
without his powers, and with the Shanti virus, he's still a
formidable opponent. Peter regained his memories so I guess he
could control his powers better after that. He seems to favour
Elle's powers though and he should have been able to access a whole
gamut of powers since he also has Sylar's accumulated powers (super
hearing, freezing, telekinesis, his scary voice (if that's a
power), turning any kind of object into a puddle...and probably
others that haven't been seen yet..think Sylar has super speed
too..and he can somehow break out of Hiro's time freeze)
