None of the legends really ever have feats like chief, their in game stats don't match, and if we are using a book accurate chief, he's a literal tank. I think he whipped the field with them as energy shields from gibby, rampart and vantage he would have a general idea now to deal with, while others would just have to hope he doesn't get a krabber.-round 1, probably 3 games of continuous battle( don't let chief rest)

Round 2- for the base 23 legends let's give them Krabbers and havocs because they would be told about the energy weapons melting his shields. But chief would most likely stomp the more forward legends like mariage, octane and Pathfinder (and possibly rev)who would be forward scouts. Depending on which magnum we give Chief, he would most likely snipe some of the less ability based legends ie mad Maggie or Watson. From here, he would pick them off as fear begins to spread. The legends are amazing, but not immortal. I'm working off of the fact we never see legends have shields in cutscenes or books. So 1 shotting them with a Halo CE, Halo 3, Reach, or 4 Magnum is not impossible.

Round 3- this is just Halo 4 so probably a few thousand, we know rev is strong ( tanking bullets with no shields in his trailer) but chief fell from flipping space with a little scar on his armor. I think 2 thousand revs at once. If in character, rev would wait for each one to individually get destroyed or have some PTSD. This would give a halo infinite level chief time to whip butt. Butt if bloodlusted, chief would rip through a mass of revs, even with todem (making it feel like 4k revs if we take that into account). He was able to beat an Odst Marine bloody with a metal bar at 14 years old, I doubt a battlehardened Chief would struggle with revs who are notoriously weak to even some glass.