Faster text:
Press Z to scroll the text dialogue faster.

Skip text:
Press A to bypass the current text dialogue.

All weapons:
Press LEFT, RIGHT, UP, DOWN at the title screen.
Then hold Z and press RIGHT(2), LEFT(2).

Level select:
Hold Z and press RIGHT, DOWN(2), RIGHT at the title screen.
Release Z, then press RIGHT, UP, DOWN, LEFT(2), UP, RIGHT(2).