All members are able to Review (Vote) on nominations.
Visit Niantic Wayfarer and you will be able to as well.
I am just a Pokemon Go player the same as you.
Staff will have a name starting with “Niantic”.
You will also see people on the forum with “Ambassador” after there name, these are not staff but volunteers that help keep the forums clean and friendly. They have several options that us "mere mortals 
" don’t such as closing threads hiding inappropriate posts etc.
I recommend that you make sure you understand criteria before reviewing and ask any questions in “Review Support”.
Make sure you review correctly, if you agree with the majority outcome then you get points which count towards you “Wayfarer” medal in game.