To play as the character from Turbo Force, do the following:
Insert your coin(s), and press and hold B+Start, and don't let go till the character shows up. At the character selection screen:
1) Press Right.
2) Press Down when the timer reaches 7 and when the nose of the plane points towards you.
3) Press Down when the timer reaches 5 and when the nose of the plane points towards you.
4) Press Down when the timer reaches 2 and when the nose of the plane points towards you.
5) Press Down when the timer reaches 0 and when the nose of the plane points towards you.
Diabloon will appear if you did everything right.