Transitioning to Overwatch from TF2

Hey, as a player moving to Overwatch from Team Fortress 2, I'd like to know what are the most important things to know about.
For example, in TF2 we play around the Ubercharge of the Medic and there are specific holds on each point depending on Attacking or Defending.

So far, I'm aware of picks although I don't really know when to run 2 tanks or 2 supports and stuff.
Also, I know a little bit about ults but they are kinda chaotic and not really easy to synchronise as people in Competitive Matchmaking don't talk and barely use the thing to show the rest of the team their ultimate charge counter.

As a start watching some VODs of tournaments or watching some of the ones that are live today would help you understand the basics. There are also multiple discords for you to find a team/ find a competitive scrim to help you learn the game through playing.

dont main a hero, main a specific role, or better play everything

Make sure to tune into player's streams if they happen to be streaming high level scrims. Helps a lot to hear the comms of top teams and such

Ults are basically ubercharge. You stack them with your team to push. Most of them are pretty good at clearing a point.

I don't recommend using Pharah's abilities willy-nilly. Rocket jumping is actually viable, and quite useful. Use it to jump up to ledges, most of which you can reach when using the rocket jump in combination with her boosters.
You can also use it to save yourself from falling off the map by boosting once or twice before using your jump jets.

Oh, and be ready for the rollercoaster ride of getting used to the wonky hitboxes on both players and projectiles...

Have fun!

Shooting feet doesn't do adequate damage, aim for directs only.

Demoman has only 1 sticky, make good use of it in combat, not only to place traps.

Sniping is a lot harder because of how much faster the movement is compared to TF2.

When pocketing Pharah as Mercy, you can toggle damage/heal in between the Pharah's shots to get the full benefit of both heal and damage boost since her damage is not continuous. It works with other heroes but you will usually be doing it with Pharah.

High ground is very important in many maps. The second part of Hollywood after the point is captured, make sure to pick a mobile hero like Winston, Genji, Reaper, Widow, Hanzo, Junkrat that can contest high ground and keep it if your team has too few or none.

A good mercy will usually run behind a safe corner to get a revive off when her team is about to die in an important fight, this is a pretty big difference from the TF2 medic. When you enter an important fight and the mercy is not there keep this in mind and try to make sure that the revive does not happen for the enemy team. Revives are very similar to ubers but require different team coordination. Good teams will all die together in order to be revived together with full health to reset the fight.

Toggle team health bars in soldier's configuration to know if your teammates need a heal or not.

Winston is the roaming soldier of Overwatch, but don't forget you have a shield. No aim, no brain, you're a Winston main.