A guardian wouldn't be able to have a super because it would have to charge. Seeing how there is a fairly long charge on a super we could bet that a guardian wouldn't have a chance to use it before the fight is over. Although, I still believe the armory of a guardian doesn't make them capable of taking Master Chief. If you've read the books (which I hope you have) you'd know that he is certainly an above average Spartan whereas a causal guardian is simply a guardian. Nothing more, nothing less. Chief excels where others don't and is able to think quicker and react faster than most. Plus, with Cortana by his side I don't see how a ghost could ever provide enough intel to get the upper hand.