It's super-rare to see him want to reprise any of his roles. Even he was getting tired of Ace Ventura by Nature Calls.
I do love the first Ace ventura.
But the sequel is ... disappointing.
All jokes, no substance.
No surprise if he feels tired of that.
I haven't thought of that.
My "idea" would be he creates Metal Sonic as a means of revenge against Sonic for the death of Dr. Robotnik. But Metal Sonic quickly goes SkyNet against him and eventually becomes Neo Metal Sonic who sends an army of Metal Sonic's back in time to kidnap Sonic. Amy is one of the survivors who go back in time to save Sonic.
That could work but I really hate how there are so many Metal Sonic in the movies.
It's like playing beat em up where you fight a cool boss in the stage 1 but in the later stages the cool boss became just regular baddies.