Oh this will be easy!!
MC and the arbiter will win this easy
Those three Spartans are Old and clunky and are trained to kill the elites at that time
MC's got upgraded armor and the arbiter to back him up and im sure the arbiter has killed a good number of Spartans (he was on reach...if i have to i'll put proof)
Also chief is marked as "hyper lethal" and the arbiter is an assassin (thats what it is)
MC and Arby WIN!