Golem Onix is the 2nd transformation of his super forms. And in a way he is more calmer and less serious in that state.
Golem onix color change to brown and all his clothes change brown also. his goggles are changed to black and his serious attitude is gone for the time being. He has only transformed into this form 2 times and never done it again. He promised he won't go that far until someone is about to die or a enemy is way to powerful for the others.
the first time onix transformed into Golem form is when he was at thhe tournament and his opponenet kept mocking him. he had enough and used his super form and that didn't work because he was to fast. After he had enough he transformed a second time and won the match.
The second time he transformed is when he was with sonic and tails when they fought against metal Sonic. When Onix saw tails on the ground like he was dead, he immediately transformed into his Golem form and obltierating Metal sonic.
Is that the best you can do?- in the tournament
Tails...no...No!!!!-Seeing tails on the ground
Never...I Never Give Up!!!!- Vs Strong Opponent
I've....done all I can- transforming back to normal