Hello everybody!
I'm sorry for the confusion, I was really tired when I created the topic and I now realize that it wasn't all that clear.
So let's start from the beginning. I'm building an arcade emulator inside a table with controls for two players.
My idea was to let each player have a joystick and 8 buttons (since I've seen some controls using this).
I also added a START button and a COIN button for each player.
Then I figured that maybe I needed to have START/SELECT as found on the Playstation controllers, but I realized that it might not work.
So this is my revamped layout, where you can exactly how I was thinking:
http://d.pr/i/8azF.

My main concern now is that I don't know which button should be 1, 2, 3, 4, 5, 6, 7, 8 on the controller. What are you guys using, and what's the best layout?
Also, should I keep the two top buttons from my previous layout and connect them to the A/B for each player? Are these used?
Thanks in advance!