Impostor Shinnok
(This is not including Predator as I have not tested options vs him)
50/50 Mixup: 5/5
*Mimicry puts you at +104 on hit, letting you teleport into NJP, b3, F4, grab, go for chip, etc. Using a bar of meter puts you at +14 on block, this forces a mixup situation in your favor. They can backdash which you can read and punish by run cancel F2, or armor which they have a 1 frame window to do and most characters don't get much from their armor, or block. . B3 and a delayed F4 after mimicry are quite effective and lead back into Mimicry vs all but 8 characters
Neutral Game: 5/5
F223 has better reach than any string in the game. F223 covers over 1/3 of the screen. Hell sparks are about half screen distance which cover jump ins. Standing 1 is a great anti cross over, D2 is a great anti air, and enhancing hell sparks puts you at +14 on block. He's negative without meter but not punishable.
Defensive Options: 3/5
Armored shoulder charge only leads to a combo in the corner, but d1/F4 are great pokes, F2 and Hell sparks are scary from mid screen. Wake up options are decent. He can armored dash which can be punished by jumping and whiff punishing but Shinnok can wake up sparks to punish that option. Very average in this category.
Zoning/Anti Zoning: 4/5
From full screen you can react to projectiles with teleport and from midscreen F2/hell sparks range are more than enough to make him strong.
Damage output: 4/5
35% bnb that leads into Mimicry into a mixup or 40% and builds back 1/3 ish of a bar if you choose to go for chip damage as well. Meterless damage is extremely low (16-23%). This would be a 2/5 imo if Shinnok didn't have access to absurd amount of chip damage. Certain match ups lead to more chip, max is about 45% but vs most characters it's 35% with 3 bars, and gains unblockable specials from a few characters. Mimicry is a standing reset so don't forget to factor in the guaranteed chip damage/meter gained back with each bnb. 41% bnb for 2/3 of bar isn't bad. I'd say it's above average.
Total: 21/25
I don't want to hear the "Impostor is too match up dependent" argument. Only one match up in the game puts Impostor at an actual disadvantage for stealing their special move and thats vs Jason. But keep in mind Shinnok gains above average/great specials from the top tiers that he is likely to face in a tournament setting.