I need to rant.
Please bear with me.
<Rant start>
Some players in Overwatch need to learn to work with support heroes!
Support are not wizardesses. They cannot heal you instantly, on-demand, even if their tech seems to work like magic. Even if they can, they may be busy with something more important like, say, backing up the two defenders you left behind holding the objective against an attack of three or four opponents!
Zenyatta is a horrible healer. Even Soldier 76 heals better than him. Do not expect miraculous health regeneration from him outside his ultimate. His healing is only good for fixing scratches. Play defensively. Watch for his discord orb and concentrate fire on whatever he is pointing at.
Mercy has high DPS. Even if she hasn't got her blaster out, she can still boost the damage of key players. Again, play a little defensively so she can contribute to the team's damage-dealing potential. Mercy's motto should be 'preventing damage by pwning the source of harm'.
Also, if you're Genji, you are very difficult to hit with a healing stream if you jump around Mercy who is trying to heal you, even with auto-aim.
It is very inefficient for Mercy to use her ultimate on only one fallen hero (unless it is a tank or someone critical at the objective). I really dislike it when there are dead bodies across the map but not close enough to resurrect with one ultimate. Stick closer together or don't die!
I've got a lot to rant concerning Ana. Turn on the health indicator in options! If you see a teammate injured, don't stand behind them and block Ana's shots from healing that teammate! And if you're injured, don't stand with your back against a wall blocking Ana's view! As long as she can see you, she can heal you. Even if you're dancing (dodging), a good Ana player will use her biotic grenade to heal you.
Don't expect Ana to run across the map to heal you. She's slow. And she can't snipe-heal if there is no line-of-sight. And she may have other injured teammates closer who need attention, who are easier to poke with needles.
If your teammate is using an ultimate, say, Soldier 76 turns on his tactical visor, don't hang too close to him! Ana usually has like 0.3 seconds to line up a nano boost shot to buff Soldier 76 and she may hit you instead!
With Symmetra, pay attention to where she places her sentries. Work with them. Lure opponents to the sentries and concentrate fire. It also helps charge Symmetra's ultimate. Usually Symmetra will place some defenses for her ultimate construction, but it would be nice if others would drop in once in a while to check.
Lucio... eh, most people work well with him. (I'm running out of rant steam.)
Lucio is good at camping the payload. Work with that. Keep threats away from him, especially Mei, Symmetra, Winston and Junkrat. Keep D.Va's ultimate away from him too. A good Lucio player will be able to hide from distant threats like Bastion, turrets and snipers but those will seriously limit his dance area, making him more vulnerable. Either get rid of the distant threats or keep all other threats away from Lucio. Keep Lucio alive and you win.
<Rant end>
Thank you for reading, especially so if you read the whole thing. I feel better.