Any suggestions for the 2D/2.5D animation software or plugins for me?

Hey all,

I'm getting back into animation after several years of hiatus after graduating college for digital animation but I don't know if there's a program or plugin that could help me animate how I would like to now. I could use some suggestions! :)

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I basically want Illustrator but with a few extra features:

1) Must still have:

a) warp/liquify tool

b) stacking layers 

c) blob brush

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2) Must have basic animation tools:

a) Keyframing

b) Onion skin of a few frames

c) easy looping 

d) multiple layers of animation

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3) In addition, I want:

a) full-body IK

b) custom skeleton and constraints/parenting 

c) lock and unlock skeleton orientation and animate interaction 

d) create like blend shapes linking to triggers/drivers [timeline, angle of joint, etc] 

e) physics and [ideally] collisions on objects 

f) change the intensity of any modification and animation with a slider like Mudbox has

.................

Lastly, it'd be amazing if it had a pipeline to work with Unity with the IK Skeleton

and Photoshop or had sufficient shading, layer styles, and masking tools.

Thanks and all the best!