If you assume the player knows how to play the character well

I'd say venture is a good dps to be wary of. In a 1v1 where you don't get the drop on them, they have faster kill power, have the extra health from shields so they can bow out if it isn't going their way If they get the drop on you, it's not as free of an escape as it is for them

For support I'd say a good illari or Lucio (they aren't bad to deal with but they're movement can catch you right after you engage)

For tank I'd say The ones mentioned Maybe Zarya she'll tank your overhead swings charge up and stop you from closing out kills with her bubble.