To unlock all apparel including shoes simply go to the Main Menu and then:

Hold L1 + Triangle while pressing Right, Right, Left, Up, Up, Up, Down, Left.
Hold L1 & Triangle. UP LEFT RIGHT UP DOWN LEFT.
Press: right, right, up, down down, left, right, left

Pause game play, then hold L1 + Triangle and press Up, Left, Down(2), Right, Down, Up, Left.

Go to the main menu and hold r1 and l1 then on r3 press up+right+up+right+down+left+up
Go to the main menu and hold l1+triangle and press on the d pad up+right+up+right+left+down+down+up

To unlock all Arenas just win all tournaments in the specfic country the Arena is in.