When you hold the triangle button and flick (or hold) the analog stick/directional pad up, down, left or right. (regular plane controls) You get...

triangle + up = "Dive Bomb" (pull up to stop the dive bomb when you desire)

triangle + down = "Somersault" (you use this in the mini game "Torpedo Run". You can't cancel out of the somersault when it's going. When you are accelerating you do a big one and a small one when not accelerating)

triangle + left = "Left Barrel Roll" (it will make your selected character do two rolls when you do this. When you hold the analog stick longer the left, you do a longer barrel roll. You'll automatically stop at a certain time when you can not barrel roll any more. It sort of works when you want to stop doing a dive bomb except that you continue going for one or two rolls then stop.)

triangle + right = "Right Barrel Roll" -see "Left Barrel Roll" description-

When you hold the L1 or R1 or both buttons and turn in the direction you want (left or right); you'll make sharper turns.

L1/R1 or both + triangle + down = "About Face" You turn around and fly in the other direction you were flying.
This is good to use if you accidentally go the wrong way. Holding L1+triangle+down makes a slow "About Face" You stay in that one spot and turn slowly (which wastes time) if not in Torpedo Run.
Holding R1 plus the other buttons make a fast "About Face" but it still takes longer.
Using L1/R1 plus the other buttons will make the best "About Face" you can do. So I recommend doing L1 & R1 + triangle + down combo.