Main: Shinnok
Best Variation: Impostor
Impostor compensates his severe lack of damage due to Mimicry which hurts his other variations significantly. He is able to put the opponent in a standing state where in addition to the high/low guessing game, you can be thrown as well. An Air teleport is able to be used as well in some anti zoning situations, although this may end up becoming more of a gimmick as time passes on. It's still an important tool to use effectively if you ever use this variation.
Worst Variation: Necromancer
What do you get when you put tracking specials in a game that don't track? You get this variation. Flick does not catch runners, period...neither does his Summoned Fiend. This will leave you frustrated against character who want to be in your face...like 90% of the cast. His unblockable takes for-fucking ever to come out and can't be normal canceled at all. I still to this point have no idea how it should be played.
Bon(e)us: Bone Shaper
In this variation we get a long range Scepter Scoop which is pretty damn fast for something with a lot of range, however, from further out in launches it becomes inconsistent and suffers from the drops far too many times than I want. His Ground Pound IMO is one of his most important specials as it makes turtling against him near impossible, plus the EX version OTG's. The projectile he gains here sucks. Does not low profile, very minus on block and hit and on whiff it's death. IMO one of the worst projectiles in the game. This brings me to his BS string exclusives, F3,1,D2 and F4,1,D2 are solid (both are safe) while F2,2,1+3 sucks as it's mad punishable on block and the standing reset from this string is not worth it at all as you're neutral and up close to the opponent which is not a good place to be.
Personally with how Mimicry functions and the low damage the other two variations are, it's merely a mandate to use Impostor if you're ever going to use this character to its true potential.
TL;DR, he still sucks.