I am building my first CP and have come up with a button layout I would like comments on.
Here is the layout for 1 joystick & 6 buttons:
(Not to scale or complete - just to show the idea)

I don't care much about fighters but I do want the ability to play them occasionally.
Here is my reasoning for this layout:
The first 4 buttons form a diagonal that I expect to work for smash TV & others (up down left right w/buttons)
The bottom 3 I expect to work well for Track n Field.
I figure the 6 are close enough to a fighter config to play those.
The 1st button can be hit with my thumb for Tron while my right hand runs a spinner.
Here are my questions:
1. Am I missing anything that is really important here?
2. What is the best way to number these that will work for most games? (123 top, 456 bottom? or 1 up 2 down 3 up 4 down, etc?)
3. How many buttons will I need across the top for other functions? ( I know I need Coin 1&2, Start 1&2,)
Here are the details of my CP:
OptiPac USB
IPac 4 - (So I can connect in with another panel later)
2 Supers
1 Trackball
1 Spinner (2 if I can squeeze another in the corner)
12 buttons for play
Other buttons (not sure how many)
Maybe 2 Pinball flippers.