CubeCraft Games

To answer your question: "what can I do?": record and report. You're not allowed to break rules, even if it's to defeat other rulebreakers as that makes you just as punishable, just report them.

You can report them for teaming. Teaming is not allowed against other players under any circumstance. I think allowing people to team on rule breakers is not a good idea. People would start to use that as an excuse like 'I thought he was cheating'. I also think if teaming up on cheaters became a thing, more people would team in general, which wouldn't be fun.

You are pretty good at pvp, you are getting called a cheater for your skills :p

Well, I think if there is someone flying around the map or not moving an inch to dozens of punch arrows/knockback sword hits, you should be allowed to team on them. On hacks that are not 100% certain, though, like killaura, aimbot, etc., it shouldn't be allowed.
Did I look like I was hacking? This is the vid: https://www.youtube.com/watch?v=Ck4qdkDeb6E

Instead of breaking the rules yourself why not focus on making the server clean?
You seem to be a good paper so I think you'll like this strat for when fighting hackers: try to back up behind a corner or pillar or smh to grapple up after about 3/4 hits you got onto him. Hackers often don't gapple in fights so you can beat 'em by doing that

I am not sure if that would be enough evidence for teaming. I have often completely ignored another player in fights to target one person because I knew they were low or I didn't want them to escape. Did they fight afterwards?

I usually kill hackers with gear advantage. My old strategy allowed me to kill hackers easily. Now, I rush players more, so I have a higher kill-death ratio and more egg kills, but it is more challenging to win as some players will have a lot of gear.
I find killing hackers with bows much easier than with the sword.

They said they fought afterwards, but neither of them died. They were both completely focused on me. Also, afterward, when I told them teaming is bannable, one of them said that he doesn't care. Evidently, he knew he was teaming.