Does all guys need visual stimulation while masturbating? Or could he just do it without anything?

No, don't NEED a visual but it does help. Being sexually focused mentally comes first in male ejaculation.

NO! Absolutely not, but it helps.

Im curious as to why you are asking this question.

Not required, definitely helps.

Porn will always help,its not needed but very much used in that aspect.Very much enjoyed as well.Kinda like the difference between wanking and sleeping with a women to lighten the load so to speak,its not always needed to have a women with you but the sensations always 100% better.