EDIT (2/10/22): I must note that I consider the Classic counterparts separate from the Modern counterparts and NOT as the younger counterparts of the Moderns
Tumblr has eaten this post 2 TIMES ALREADY SO HERE I GO AGAIN:
I wonder why are my character ideas/ AUs so complex. Like I literally just changed Sonic Heroes (1 difference being that it's on Classic Mobius (home of the Classics) in the Normalverse (main games Sonic AU) ) and made Neo Metal (Classic) a separate being who was created when Classic Metal absorbed the negative energy of the Chaos Emeralds and Metal was helpless to do anything while Neo Metal caused chaos and hurt Classic Robotnik (until Classic Robotnik escaped) until Team Sonic and Team Rose (Classic Amy and Classic Big) along with Eggman's help weakened him enough for Metal to try to detransform which partially happens because Neo tries to kill Classic Robotnik.
Knuckles explains what's happening and that Metal is risking destroying his own mind to forcefully expel Neo out of his body.
Metal battles Neo and is able to hit him more than 20 times and weakens him in 10 minutes and runs a short and short time limit jumping course while his mind is being destroyed, and makes it and Neo is expelled from his body. (temporarily as long as Metal doesn't use the Chaos Emeralds, which Metal only does when forced to. However, three other of my AUs don't end so well) I did this because I wanted something other than rebellious Metal Sonic being Neo. Also, the Neo thing takes inspiration from my favorite Sonic fan game, Sonic.exe Nightmare Beginning, this AU specifically taking the best ending and the other three AUs takes inspiration from the badder endings