Roadhog has to be one of the slowest heroes to play on Overwatch 2. Not only has he received a recent buff that has made him less lethal, but his overall mobility is rather poor, including his ultimate ability movements.
Roadhog has a movement speed of 5.5 m/s (meters per second), while his "whole hog" ultimate ability lowers his mobility to an extremely low 2.5 m/s. This makes him generally the slowest hero (and worst ultimate speed), giving a rather large advantage to the enemy team. Roadhog may be one of the hardest heroes to play, but learning his counters in Overwatch could assist in dealing damage for better crowd control abilities.
Zenyatta is second to Roadhog, although he is still considered one of the slowest support heroes in Overwatch. Zenyatta is always behind everyone else, while his rapid-fire ability is also extremely low compared to other heroes.
Zenyatta has an average of 5.5 m/s similar to Roadhog (and most other heroes), while his ultimate ability (transcendence) also sits at 5.5 m/s. Compared to other ultimate abilities such as Lúcio at 11.1 or D. VA sitting high up at 12.5 m/s (for mech booster), Zenyatta really stays near the slow end.
Zarya is another slow tank character in Overwatch 2. Although she is a rather good tank hero, she is unfortunately pretty slow. Not going to lie though, dealing damage is one of her strongest ultimate abilities, and she has been pretty OP in the past few months as a tank.
Zarya averages around 5.5 m/s even for her ult, which makes her another hero who could be last to show up for team fights. Although most tanks are pretty slow, Zarya is really difficult to keep in the front as the main bull.
Torbjorn is a pretty effective damage hero, although against the enemy team, he is one of the slowest damage heroes to play with. As you learn how fast other enemies are, you will realize the Torbjorn is a sitting duck.
As Torbjorn averages at 5.5 m/s, he has no sprint or running boost. From my experience, I have found it really difficult to catch up from respawn with Torbjorn, unless I have a Lucio helping. I really do not recommend this player if you are in a rush to get to the control point or escort in time, even with his ult, he has limited range for attack.
Sigma is absolutely fantastic to counter many different heroes, especially the slow enemies. However, if you are stuck and surrounded, you have no way of saving yourself.
Tank heroes like Sigma need to be learned rather quickly, as he is a close-range and high-damage type of hero who requires a lot of combo knowledge. Sigma is really slow at the start, and can pair really well with a Lucio to help him get to the control points faster. I always have Sigma players ask me as a Lucio to use his speed boost at the beginning of every match, which helps a team significantly in advantage.
Widowmaker is already hard to judge because of her sniper, but her run is also just as slow as everyone else in this list. Widowmaker is extremely hard to avoid enemy team damage once she is down the sights.
Not only is Widowmaker slow, but she is also one of the hardest heroes to play in Overwatch, making her an easy target for her counters or fast Overwatch heroes like Lúcio or Reinhardt with his charging ability. Unless you can learn how to mitigate damage to the opposing team or try to achieve crowd control ability, her primary fire will be your best bet in game modes.
Bastion although last in this line-up, does not exclude the fact that he is one of the slowest heroes to play Overwatch with. Bastion has abilities that can ultimately slow down his overall approach to the enemy team leaving him vulnerable in game-turning situations.
Bastion runs at the average of 5.5 m/s, although his tank mode (which is used rather often by Bastion players) puts him at a lower if not the same speed. Without any type of speed buff for this recon character, you really need to watch out for possible overruns from the team.