TL/DR: Bastion's main problem is being taken out of the fight by a dive. This can sometimes be mitigated with the help of his teammates through different defensive abilities.
To help make him less drastically reliant on his team and more viable not only against dive comps, he should get one of three tools that would give him more options for counterplay against the other heroes: Offense, Defense, or Mobility.
Click the triangle at the top right for a more in-depth walkthrough.
Bastion’s main problem is that if he gets dove on, he will almost certainly die. He can’t avoid this on his own due to his low mobility. He can try avoiding this with the help of his teammates with something like a Reinhardt shield, Zarya bubble, or massive amounts of healing. You can also totally ignore the dive and instead get resurrected by mercy. However, with mercy’s recent changes that’s less of a possibility.
Out the number of ways we have, all of them involve Bastion relying solely on his team for survival. The way to make him less reliant on his team is to give him a tool of his own to counteract a dive. We could do this in a number of different ways. There are three ways that I can think of to prevent or dissuade enemies from diving on you:
Offense - A temporary increase in fire-rate bound to an E ability
- Overclock
- Cooldown: 8 seconds
- Duration: 3 seconds
- Cast time: 1 second
Bastion can counteract a dive as well as be more effective against tanks and barriers while using this. Since your spread will stay the same, squishies (or 200 health targets) will not be good targets because of all the potential damage you’d be wasting. They could also just avoid your attacks by using a movement ability or just disengaging and then you’d be left with few resources to prevent their subsequent attack. In the situation of a typical dive, this would be super effective when used against a diving Winston or D.va trying to get in your face.
As a side note, it also adds another layer of skill to the hero by introducing ammo management. Ammo isn’t typically a concern for the current bastion as he usually has more than enough ammo to last during an entire fight. You may often find yourself running out of ammo more often than usual! Reloading at inopportune times can cost you the fight or worse, the match.
Defense - A temporary increase in damage resistance bound to an E ability
- Siege Tactics
- Cooldown: 8 seconds
- Duration: 2 seconds
- No cast time.
This will put Bastion into a more defensive role. The important part of this ability is that it gives Bastion the opportunity for counter-play to abilities like hook, sleep dart, and charge. In the situation of a dive, instead of trying to disengage, you will have to time this correctly to take on the full brunt of the assault. When the enemy D.va, for example, dives you, you should use it when she uses her micro missles. If you are lucky, you might get a Gengi to waste his dash during that period.
Mobility - A temporary increase in movement speed bound to an E ability
- Overdrive
- Cooldown: 10 seconds
- Duration: 4 seconds
- No cast time.
It would perform like a temporary Lucio speed aura, except it only works for you. Using your ability can help you get into positions quickly on control maps, for example. This would also be Bastion's get out jail free card if he finds himself being dived on or focused heavily. In the situation of the dive scenario, you would use this to escape their dive as they use all their movement abilities trying to get to you before you re-engage.