OmniSpectra
I'm confused he is supposed to be overpowered and yet he is weaker than cooler if it was like this than you should change the tag from overpowered to weak to strong it's already 41 chapters in and he is still weaker than people who he shouldn't be I'm not saying to make him more powerful than beerus or god-forbid wis at least not now
Honestly this is the better outcome, Cooler is not going to kill him soon though he will definitely try once Zyleth becomes too strong but joining him now is going to be a nice reprieve where he can grow stronger, plus now he just needs to master his evil transformation and unlock others and time is the only thing he needs
I have a small piece of advice for you, Mr. Author. I believe it is during these types of arcs where you have to imagine much more complicated developments with certain characters that don't appear much in the series that the mind gets burned out and gets tired of writing. So, if you feel like that, take your time, or even go on a hiatus to stockpile chapters. Otherwise, it might lead to simply dropping the story. Which would be a real shame since you are really cooking here.