Is Strong PC Muscle Mandatory for Super-O?

I use do nothing, do not focus on pc muscle, and I achieved a super-o. Could be, the trained pc gives even better results? But mine were very good, best orgasm of my life no doubt.

So I'm doing while I lie on my back. I only managed to get somewhat nice feeling that makes me feeling really comfortable, then uncontrollable shiver and moan. But that doesn't last long, is this what you guys call P-Wave?

Yes, the "...nice feeling...feeling really comfortable,..." part of your statement would be considered a P-wave, the shiver and moan are just types of body reactions you may encounter along this journey.

Correct me if I'm wrong, I think to get the Super-O one must have a strong pc muscle.

NO, this is incorrect. Some men have been able to experience a Super-O in their very first Anerosession without having developed strong PC or BC muscles. However, with that being established, developing strong PC/BC muscles will enhance the strength and intensity of your future orgasms, as well as enhance your ability to achieve them.

So whenever there's a newbie trying for first time, they most likely failed because they have untrained pc muscle. Am I right?

NO, there may be a multitude of reasons for failing to obtain a Super-O, especially upon initial usage. Please see the thread Identifying Obstacles to Progress or an introductory listing of such reasons.

is having a strong pc muscle mandatory for getting that Super-O? if yes, then it would take such a long time for strengthening the pc muscle

NO, it is not mandatory as I noted above.
Good Vibes to You !