hit start when you are playing, then hit select 16 times. then ypu shound see a box. hold a+b to move the box. when it is on something hit up to higher it. (all the away to the left next to the lives is wario and put the box on him then you will get the next weapon)
Cheat
Wario you pause the game. Then hit select 16 times until a little square pops out over at the bottom of the screen. After that you can hold A and B together to move the square around using the D-Pad pressing up makes the value larger and down makes it smaller. You can also put the cursor over wario head (on very left) and press start. This makes his hat one step higher.
Get The Best Ending
You think the Castle is the best ending you can get? No way! Collect all of the treasures and get 99999 coins. Now beat the game. When the genie tells you to go look at your new property and Wario goes there, nothing is there. Then Wario will float into the sky until he gets into space. He will then land on a planet with his face on it! When all that stuff happens, you've gotten the best ending!
Note: If you got the castle ending instead, you probaly missed a treasure or didn't get enough coins.