I would even go as far as saying that Bone Shaper probably has everything you need. I am an Impostor player myself but I have to admit the superiority of the Bone Shaper in terms of safe blockstrings and meter building, which is very important for Shinnok in general. Impostor gets that teleport, restand at +104, stolen moves (vortex sometimes), and damage buff which is awesome for huge chip damage, combos and 16% throws. But when you have no meter you can't do anything safe on block. He builds meter with blockstrings which require meter in order to at list creat the threat of a MB Spark in the end.
Bone Shaper has safe strings with more hits, builds meter fast, has that projectile to make everything safe on block even without meter. And now has a standing reset which leaves him at +8 which guarantees the f4 follow up. So it is a weaker reset/mix up than that of the Impostor but it goes back into the standing reset on everyone in the cast. Plus Bone Shaper zones better than Necromancer and has a wake up/reversal attack which is armored, leads to a full combo into satnding reset, and works as a great antizoning/whiff punishing tool as it reaches 90% of the screen.