All Weapons

Press Left, Right, Up, Down at the title screen. Then hold Z and press Right(2 times), Left(2 times) then while playing the game press a+b+r

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Level Select

Hold Z and press Right, Down(2 times), Right at the title screen. Release Z, then press Right, Up, Down, Left(2 times), Up, Right(2 times).

All Weapons

Press Left, Right, Up, Down at the title screen. Then hold Z and press Right(2 times), Left(2 times) then while playing the game press a+b+r

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Level Select

Hold Z and press Right, Down(2 times), Right at the title screen. Release Z, then press Right, Up, Down, Left(2 times), Up, Right(2 times).