I really can not play Zarya when solo'ing I just get destroyed
Zarya is one of the few characters I can carry bad teams on. At least until the other side figures out they should just save their ults for me.
I'm still working out who are the best characters to play when I'm in a really bad team.
Lucio - great at surviving and holding down objectives, which is important when your 2 Mccrees and Genjis are off in a corner of a map playing a game that isn't Overwatch. I held a point with a Roadhog last night and never even saw any other teammates. If you do die, he's very fast and can get back quickly.
S76 - can operate on his own pretty well and like Lucio is fast and can respond to the objective quickly. He can beat most other characters which is important when you never see your teammates. Ult is good for singling out healers (because nobody else will shoot them first).
Winston - Oddly enough I had a ton of success with him last night. In solo queue there's always at least one sniper and one genji. He's also great for dealing with Tracer, who most randumbs seem to
ignore completely.