You need to get all of the stars and use the wing mario power in the front of the castle
out of the canon and smash into the spot where the black box is then waluigi comes out

Ohhh. I'll try that... But i haven't got the stars yet... 'donkeyoil', have you done it
yet?

I haven't tried it yet but i found that on multiple websites

Jump in the wario picture defeat chef chilly go and get luigi and go to courtyard where
the luigi rabbit and there will be a plat form and go on and go in the waluigi picture

I'm reading all these answers but do you need one of them cheat things for your ds? Happy
gaming :3

Hes real!

On youtube channels look up wwwario or arceus2401<--has waluigi