Due to Overwatch's nature as a very team-based game that revolves around picking the right Heroes for the task at hand, it is often not enough to merely know how to play a new Hero. Oftentimes, a lot of the discussion surrounding the game's newest Heroes involve figuring out how to counter them or, conversely, how to organize a team comp around a Hero's strengths and weaknesses so that they don't turn into a giant liability that only exists to fuel the other team's Ultimate abilities. As one may expect, Doomfist is the latest Hero to come under such scrutiny, as his unique abilities demand unique counters.
For starters, Doomfist can best be described as a beefier Genji, in more than one sense of the word. His abilities give him the opportunity to instantly kill a large portion of Overwatch's Hero roster, and if left unchecked, he can single-handedly decimate a team with a flurry of combos. In fact, so much of Doomfist's lethality comes from Rocket Punch that it might as well be his primary attack, which would probably explain why Blizzard decided to give him a three star difficulty rating. For all intents and purposes, Doomfist's maximum effective range is thus locked to 20 meters, as that is the furthest that he can travel with Rocket Punch. While it is true that Doomfist can combo his abilities to let him travel some 40 meters, this puts all of his abilities on cooldown, which can be rather disastrous if he finds himself in the midst of an enemy team.
Unfortunately for Doomfist, this means that Sombra can completely shut him down with a well-timed Hack, as his Hand Cannon is rather mediocre at best at any range greater than 15 meters. In addition, while Doomfist has an ability to generate a personal shield upon damaging enemies (giving him up to 400 health at most), he has no real defensive abilities, as he can't outright negate, avoid, or reflect damage. Considering how Doomfist is roughly the size of a Training Bot, it would be a real challenge for most Heroes to miss him, which in itself might be enough to discourage Doomfist from charging straight into battle.
Unsurprisingly, Doomfist's highly aggressive playstyle and short-ranged nature makes him extremely vulnerable to Pharah. For that matter, any Hero that revolves around long range and raw DPS (i.e. highly skilled Widowmakers or well positioned Bastions) can simply shoot Doomfist to death before he reaches lethal range or at least force him to attack from some other direction. Alternatively, you can choose Heroes like Reaper to make the prospect of charging your team so dangerous that Doomfist will have no choice but to switch to another Hero. Any Hero with some kind of disruption ability such as McCree's Flashbang, Roadhog's Hook, or Orisa's Halt! can literally stop Doomfist in his tracks (although you still might not want to pick Roadhog), as can any Hero who exists to counter overextension, such as Zenyatta. Overwatch's poster child, Tracer, can also prove to be highly annoying, seeing as how Doomfist's abilities perform poorly against fast-moving Heroes. If all else fails and you can't outright kill Doomfist, so long as you can force him to use his abilities to escape, then that would be a beneficial outcome for your team.
With so many apparent counters, it really brings up the question of just when and how should Doomfist be used. After all, he's a terrible anti-flanker, he has no range outside of Rocket Punch, and his Ultimate ability, Meteor Strike, is not nearly as threatening or independently game changing as its name implies. Realistically, the best way to use Doomfist is to utilize him as a Tank destroyer in a dive comp, as Winston can (kind of) deal with fast targets, and D.Va can protect him as he uses Rocket Punch. Doomfist might also be useful on maps that have a lot of corners and objects that you can Rocket Punch people into, but in such a situation, Reaper might prove to be more versatile. In any case, it is almost mandatory to have a Soldier:76 on the team to handle long-range threats or to soften up targets before Doomfist reaches them. At the very least, a team should ideally be able to isolate and corral people into confined spaces so that Doomfist can throw people into walls, which, as the Overwatch World Cup Qualifiers proved, is one of the many strengths of a dive comp.
Regardless, it is clear that Doomfist is going to be one of Overwatch's more difficult Heroes to play against and with. His high potential impact makes him a rather high priority target, and the threat he poses to your healers is not to be underestimated thanks to his potential mobility, but it seems as though he's going to be another high-risk high reward Hero that penalizes inexperienced players on both sides; those who can't play Doomfist but are stubbornly staying on him are just going to get annihilated, and teams who can't communicate to take him down before he does too much damage are similarly going to get dismantled.