If you don't already know who Omega is I'm gonna put his character bio from his first game in Japanese and here's Sonic Channel for safe keeping lol.

Sonic Heroes: 

The final lot number of the E-series robots built by Eggman, and the most powerful. Despite having the strongest power, Omega has been sealed up in the base for a long time, and he holds a grudge against Eggman for that.

 He aims to prove himself “the strongest” by destroying all the machines created by Eggman, and to take revenge on Eggman who sealed him up. When Rouge awakens Shadow from his capsule, he is unsealed at the same time, and they work together. He has a strong body and two sturdy arms, and can transform his arms into various weapons for a variety of attacks.

The final lot number and most powerful unit of the E-series robots created by Dr. Eggman. He transforms his arm parts into various weapons, annihilating enemies with overwhelming firepower.

Having been sealed away for a long time immediately after his completion, he harbors intense hatred for his creator, Dr. Eggman. Omega’s purpose is to destroy all of Dr. Eggman’s machines to prove his own supremacy, and to exact revenge on Dr. Eggman for sealing him away.

For a reference of the voice I want you to imitate here's a playlist with all Sonic games in Japanese.

Solebinku's Personal Direction:

Just make him sound deep and ferocious as a robot don't worry about making him sound robot like just add a filter lol. You can sound as animate as you want like heroes does, no need to be plain robot he has a fiery energy. 

Japanese is always the good reference so look at that to get what I mean.

Game Cutscenes:

https://youtube.com/playlist?list=PLhnIPa8XAn7x6g8UvkO0UaiTHtK-VBUbd&si=gTudY2rorUzd7vGB

General Omega voice lines.

https://youtu.be/MJawJDY3V2A?si=Oc4vYR3U22WOHWtp

https://youtu.be/U0U1joNP13U?si=1DitlIxCpfwLPPEM

If you want to learn more about the character I made a video for him on my YouTube channel:

https://youtu.be/JhGG4ighWcM?si=BW-8IIx-p7ekZcPK