Joker seems to have a ton of nuance, so much that you're going to have to put in more work in the early stages to start seeing results compared to the intuitive nature of the rest of the cast. I'm new to Injustice, but from what I understand the things that made joker bad in the first game were the inconsistent/glitched out nature of his hitboxes. Seems like they fixed those issues and added some buffs with the only downside of losing that flower move (looked pretty strong in the first game).
We also have Alioune and Notez to help develop an optimized joker
Anyways, wouldn't it be optimal to end his midscreen BnBs into sweep? The hard knockdown gives us an ambiguous left/right mixup followup or at the very least guaranteed pressure. Sonic fox did a followup to MB Canister with B3 D2 Teeth into 324 D3 and got a safe jump. If you inch forward slightly after the sweep, you can time the Jump 2 to hit in front or as a crossup at the same spacing.
There's also the potential of the 21 hitconfirm, since there's a lot of possible decisions to make after it being blocked. Can just go into 212 for the safe teeth/mb canister/crowbar cancel, b1 for the gunshot hitconfirm (or you're getting punished), jump, ect.