I think Vulcans already have enough superpowers, but if I had to pick one, I think that the ability to stop time would be useful (assuming that they could still move outside it)
Prepare for trouble...
...and make it double!
To infect the world with devastation!
To blight all peoples in every nation!
To denounce the goodness of truth and love!
To extend our wrath to the stars above!
Tahlin!
...and... er...Tahlin!
We're Team Rocket, circling Earth all day and night!
Surrender to us now or you will surely lose the fight!