Your stationary what?
My most recent addition to The Great Fixing Thread was a remake for 3* Hulk (https://forums.d3go.com/discussion/comment/675384/#Comment_675384)
The tl;dr is Hulk deals damage back based on how much he receives via the magic of Countdowns. In a way, it's close to the idea behind managing the "transform" countdown for 5* Banner.
I think that the Banner form probably needs an additional means of speeding up the transformation (either generating Green AP or reducing the timer on CDs when he takes damage). As for Hulk, I wanted to come up with something that's suitably 5* tier worthy: give Hulk form a passive which makes him immune to all damage, but reduce his health by x% each turn. Basically, a countdown timer which cannot be modified or removed. Make it so that Rank 1/2/3 of Hulk form reduces health by 33.33% per turn, Rank 4 by 25% and Rank 5 by 20% (that's 3/4/5 turns of damage proof tank every time Banner transforms).