I played about ~50 games with bots to see how well they do against each other
Moji - Moji's strength comes from his splash damage and magical barrier. Since bots rush to the point, Moji's splash deals lots of damage and allows her to generate her ult really easily. Also, bots tend to feed Magic Barrier so Moji has great burst potential most of the time,
Barik - Arguably the best Tank for bots. His turrets have autoaim and he deals a lot of damage for a tank. His shield is also very potent
Lian - Because no bot can actually aim with their weapon, Lian's Alacrity talent and general autoaim combined with the fact that bots group together makes her damage output enormous. Also, her ult is one of the best in the Bot Meta since nobody knows how to deal with it, and it charges fast due to the fact she damages multiple enemies,
Ruckus - Ruckus is surprisingly really good with bots. He normally dashes around firing his guns. His playstyle is basically diving on an enemy and spamming all his abilities. His ult is where a lot of his power lies. He manages to charge it really fast due to an aggressive playstyle and since bots tend to stand in plain sight of him, gets multiple kills with Hexafire.
Tyra - Fire Bomb is arguably one of the best abilities in the Bot Meta. Bots always like to stand in it, giving Tyra some free damage. Mercy Kill is really good against bots due to the damage it does and how Nade Launcher never misses since bots always walk forwards in lines.
Ash - Splash Damage is really OP in the Bot Meta because all bots group up and rush to the objective. This gives Ash a very high damage output and very fast charge rate. Her ult is also really good since when her team is losing. Since bots don't group up, Assert Dominance guarantees 8 seconds for your team to come and prevents Ash from staggering herself even more.
Furia - If one thing is for certain in the Bot Meta it's that healers have very little healing. However, Furia is one of the exceptions. Because her healing is on a low cooldown and has a lot of range due to Cherish, she actually can get a good amount of healing over a match. Since bots tend to walk in straight line, Pyre Strike almost always connects to 2 or 3 enemies, giving Furia some very good CC.
Grover - Grover has the highest healing output out of all the healers. Because he doesn't have to use an ability to heal and all his teammates will have grouped up with him on the objective, Grover's healing skyrockets. His damage output and other abilities are weak, so he is not in the S+ tier.
Seris - Despite being a support, Seris' healing is very mediocre. It's not non-existent, however her true power comes from her damage output. She is a very good duellist to bots, with Rend Soul healing her up for a second life. She also has splash damage, which, said many times before, is a very good mechanic to bots. Her ult is also fast charging thanks to splash and because bots don't know how to counter it, is very game changing as well.
Inara - Inara is the best tank at holding down objectives. Her high health and abilities make her a tough target to take down. Her Wall normally gets placed in the enemy midline, and staggers out enemies. She is just in general a very well rounded character for survivability and disruption however he damage is only medium.
Grokh - Grokh, like Seris has very minor healing and very high damage. His bouncing ball means he damage so many different enemies and his beam has an autolock mechanic. His ult is also very good at teamfights which always happen at the beginning of rounds.
Khan - Bots cannot aim. And then there's Khan. I don't know what sort of special programming Evil Mojo added to him however he hits a lot of his shots, resulting in high damage and fast ult charge. He also tends to have his shield raised most of the damage which paired with Lian's Shield makes him a solid Point Tank option for bots.
Buck - Buck is very good at not dying. Out of the flanks, he is the most self sufficient. Buck bots also for whatever reason, use their ults in completely appropriate times and get a high amount of kills.
Vivian - Vivian is basically an off tank. She has a great weapon, giving her a lot of damage. She also has a thin hitbox and shield, giving her great survivability. Only downside is she normally ults in very bad situations.
Evie - Despite Over the Moon rarely making a difference, Evie's reliable base weapon is what makes her good. She normally blinks into the enemy team, fire 3 shots before they notice her, Ice Block for 3 seconds as the enemy bots forget she exists and Soars into her team to continue firing shots. Unfortunately, the power of Lian and her Autoaim kind of damage her reliability however she is still a solid option
Pip - Splash Damage and very good burst healing, higher then expected
Viktor - Farms Barrage and gets multikills with it. Cardio also makes up for terrible healers.
Talus - Escape makes up for no healing support from team. He also has one of the best weapons in the bot meta
Maeve - Bots tend to pounce, daggers, 9 lives, pounce and daggers again giving Maeve a high amount of Burst. This makes her a very good flanker.
Terminus - Term has splash damage which makes his usually slow charging ult surprisingly fast. Bots also stand there during re-animation so he gets multiple kills. He is unfortunately weak without his ult.
Kinessa - Despite having a tendency to walk forwards onto point and die, Kinessa always scopes to take her shots. This gives a great amount of burst damage very 2-3 seconds. She also uses her escape to actually escape from combat. She is however helpless against flanks.
Strix - See Kinessa
Jenos - Jenos is a hybrid. HIs healer is relatively minor like his damage however it's enough (and more importantly, more then what other characters provide in the Bot Meta)
Dredge - Spam, Spam, Spam, Kill, Double Triple, Spam Spam Spam. He does suck against flanks however
Skye - Bots are unable to use stealth to it's full potential, which is unfortunate since when Skye turns invisible all bots forget about her existence. Her damage is bad however her ult does pick up multiple kills.
Fernando - Fernando is an off tank. He always cancels his shield early but makes up to it with great damage and health. He also has splash damage.
Cassie - Cassie bots are blessed with the gift of not rushing into the enemy backline and dying. Instead, she spams arrows onto point. Her ult is extremely useless in the bot meta and her kit is rather weak.
Atlas - Someone should probably tell Atlas bots they don't need to charge up every shot before missing it, making their damage output low. Thankfully, his abilities give him great Stalling and Survivability, making him a good point tank option.
Makoa - Makoa, despite being a must ban among humans is a niche pick for bots. His hook never actually hooks anyone useful and always misses shots, resulting in a slow ult charge. His shell however, is what makes him a very good point tank option. It allows protection for the whole team, making him a very good point tank.
Lex - Take Lian, but make the autoaim weaker, make the weapon worse and make the ult useless. You end up with lex. He is useless against most champions but is a very important champion when it comes to countering thin hitbox characters. Unfortunately, Lian is 99% of the time the better option
Drogoz - We are now entering the category of bad champions. Drogoz never makes use of his Fire Spit or Flying mechanic. He also never ults in an good moment.
Raum - Raum basically just charges into the enemy backline and dies since he has very little defensive capability. His ult is one of the better ones however his reduced movement speed when firing makes even bots with the worst aim able to hit him.
Torvald - His shields never seem to make a difference. His ult never seems to make a difference. His presence is just underwhelming. Silence does do a good job against Moji, Lian and some of the high tier heroes however he is niche at best.
Imani - Imani bots walk forwards and die. Simple as that. Occasionally throwing a frost bomb but more or less of the time dead.
Willo - Willo's abilities are completely wasted by the bot and her ultimate never sees actual play. Her base weapon does to splash however.....
Zhin - Zhin just spams all his abilities and Whirlwinds into the backline and dies. His ult is a guaranteed kill because of Guillotine but his utilities outside of that are limited.
Koga - Another champion of the list of people who dash into the backline and die
Andro - See Koga
Mal'Damba - See Andro. Also, 90% of his healing and damage comes from his gourd (which is a really low amount)
Io - See Koga
Sha Lin - Kinessa - Aim = Sha Lin
Ying - Ying bots always shatter her illusions whenever she can, resulting in 0 healing. She also has bad aim
BK - No