I've tried since the launch of Injustice 2 to find the perfect AI simulator setup for my AI simulator team. Sometimes I've succeeded, and other times I've failed using the same three character team with the same static stats. What's odd is that like a match against a human player even once promising AI constructs in similar match-ups were beaten regardless of former victories under similar circumstances. Hear me out a moment. At one point (using the same setup) my lvl.20 Aquaman beat a lvl.20 Batman, but going against the same character with the same level, and moves later on my Aquaman ended up fighting differently, and lost as a result. Ultimately as a bi-product of becoming more negligent, and careless with the actions, and reactions he/it applied. The latter Batman also did as the former batman tended to do, only switching things up as to not mirror every other Batman, but more effectively so due to my Aquaman's missteps. All the while with my Aquaman harboring a similar brawler type setup as this Batman AI obviously had.
What you have to take in account is that players tweak 6 stats up to 30 points each, but limited to a total of 60 points altogether. Points which are strategically allotted to make the AI character behave in a certain/specific way in the unmanned matches. These are strategically assigned, and more often than not players will adjust the stats as appropriate for the type of character they are putting into a match. A couple of examples being that a zoning character will get a decent amount of their stat points allotted to zoning, and runaway while characters that are brawlers will get more stat points assigned to rushdown, combos, and counters. All because the characters are more efficient with certain play styles. Thus is the "programming" to act, and react in specific ways, but not in a truly adaptive AI mannerism.
While there is the player set static stats options in play you also have to consider that character, and character match-ups must be considered as well in a true to AI build. As with most fighting games Injustice 2's roster is constantly unbalanced to one extreme or the other in this regard, and unreliably so. I believe this is where the faux AI simulation begins to breakdown due to hidden random elements. Some character match-ups will almost always favor one character or the other naturally due to the exploitable nature of said base character, and their locked in move sets in association with their movement/reach until they are patched. Both in the faux AI, and player controlled sense. This alone presents a problem when it comes to the faux AI simulator though. While there are player set static variables in the stats setup as well as the grounded basic mechanics and fighter types the AI you program through stat setup fails to properly comprehend, or learn to respond to any of the other non-static aspects such as character base stats (str, abl, def, hp), health bar/super gauge levels, or character patches. Even through repeat encounters the encounters themselves are hit or miss though often times only slightly different.
This shows a lack of what an AI is. A proper learning machine with the capacity to adapt to a situation with increasing intelligence, and accuracy. In this the faux AI simulator within Injustice 2 fails as it relies wholly on randomness in light of a player set static arrangement to seem as if the programmed character is actually making intelligent, and educated decisions. Intelligence which definitely is not shown in a consistent enough manner to warrant such an assessment. Without proper adaptation, and learning Injustice 2's AI simulator is nothing more than an automated, random, and limited CPU character factory with tweakable parameters that make it seem as if it is learning the ropes of the fight. A fake fight that is often times thrown for the sake of the developer looking as if they mastered video game AI.