Play as Shiki. 
Put the cursor over the Random box and press Up, Up, Down, Down, Up, Down, Down.
(code can be accessed by beating 1P Mode on Hard difficulty)

Play as Zankuro Minazuki. 
Put the cursor over the Random box and press Down, Down, Up, Up, Down, Up, Up.
(code can be accessed by beating 1P Mode on Normal difficulty)

Forfeit a round.
By pressing A and B to dodge, then pressing Up twice, you're character will forfeit a round. 
Although, the next round you start you'll have Max Power Gauge.

How to pick up your weapon.
When you have un-equiped yourself or if your weapon has been knocked out of your hand, go next to hit, and press the A button. You're character will be temporarily left open to attact, while they are trying to pick it up.

How to Un-equip yourself
To un-equip yourself of your weapon, first press A and B together to dodge, then press down, down. 
Your character should do a little taunt, of sorts, then put their weapon into the ground.