Gamemodes I Recommend You Use This In:
All of them are perfect for this method

Skill Level Recommended:
250 Hours+, Lv30+

This method is one most found in casual matches, and is probably one of the most used methods, and maybe the most effective.
How you do this is simple, you equip any gloves which are not stock, i advise killer gloves of boxing for all the methods, but your preferred could work better. Then you set a target and run up to them, swerving from side to side so you have less chance of dying on the way to them. Then you inflict your first punch, then inflict the amount of punches needed to kill the enemy. As a class with high health, this is quite effective as it means you die in a slower time. Beware though, as you should always keep moving around your enemies to keep them on their toes, and you should be careful for snipers and spies. DO NOT ATTACK AN ENEMY IN A CORNER AS THIS LEAVES YOU OPEN AND CAN LET THE ENEMY ATTACK MORE OFTEN!! This method requires a very aggressive play style and slick movement. A slight disadvantage of this is you may get less kills per life, as half you health may go per enemy killed, yet this could be made less of an issue using a Dalokahs Bar.

Method Rating:
8/10 - "Perfect for aggressive playstyles"

Gamemodes I Recommend You Play This On:
All casual modes, but not MvM.

Skill Level:
20+ hours, Lv10+

This is method for people with a lower skill level, or more cautious players. It is a bit easier to pull of than the aggressive methods, but does rely on key movement. How you do this method is fairly straight forward, simply walk to the side of an enemy, and walk forward to inflict a hit, then back away and wait a few seconds, continuously moving while you do this. Then keep repeating this methods until you get a kill. This method may get you less damaged, but could result in a longer time defeating the enemy. To counter this, in your second slot, equip a shotgun type and inflict the final blow with it. You may get a higher killstreak, but it may take longer.

This method could be used in partner with the aggressive method & you require the killer gloves of boxing, for the pagressive method. This method is getting a first kill using the passive method, then with the new found crits, do the aggressive method on everyone else.

Rating:
Passive - 6/10 - "Perfect for killstreaks"
Pagressive - 9/10 - "Excellet for aggressive and passive playstyles alike"

Gamemodes I Recommend You Use:
Medieval Mode! ONLY Medieval Mode, unless your REALLY good!

Skill Level:
Medieval Mode - 3 hours, Lv2
Casual Mode - 100 hours, Lv80

Please don't do this in a casual match, unless your a god. You need to have the buffalo steak sandvich equipped in your secondary slot, and any gloves you think is your best. This is primarily seen in medieval mode for 2 reasons, its quite effective & actually beneficial to your team. If you use this in casual, you will be making a huge mistake. It is not very beneficial, and is not the best for your team. If you have it in a casual, you are wasting your time and you should instead use your minigun.

However, this method is still an okay option. If your really good at TF2, this could be very beneficial and could get a huge killstreak. Only do this if you have alot of experience. Another option is Medieval Mode, where this is primarily useful. It is very helpful to the team, and is really fun. For this method, just do what you do for aggressive mode. The recommended gloves are killer gloves of boxing.

Rating:
Casual, low level - 3/10
Casual, high level - 7/10
Medieval Mode - 8/10

Gamemodes I Recommend You Use It In:
Any, except MvM (cause you can't)

Skill level:
Any

THIS METHOD IS WHAT YOU SHOULD USE WHEN THERE'S 2 HEAVIES FIGHTING EACH OTHER!
This method is similar to the passive method. What you do is have a head on 1v1 match. In a duel, I recommend using killer gloves of boxing. What you do is stand face to face, constantly moving. Occasionally move forward and inflict a punch. Keep repeating these steps until a death occurs. This is a risky strategy as winning relies purely on hit damage and random crits. You should only use this against other heavies who are looking for a duel with you. This isn't the most reliably strategy for your team, but more reliable than the Buffalo Gloves strategy.

Rating:
6/10 - "Perfect for 1 on 1 combat"

Thank you for reading my guide! It is the first one I've done, so it may not be the best. Have a good day.