Theres also a way with wario and yoshi ill start with yosh-yosh
Go to the place were you went with luigi and climb the nearest tree to the green hill have your back facing the green hill and jump then do the air run onto the green hill until you reach a green ledge that you can stand on (i think) then jump so your back is facing the green hill and keep air running till you reach the top!
Now for fatty "i need jenny craig" wario (i just needed to get that out)
go to the place were "Jackocheatie94" mentioned and go to the green hill double jump onto the hill and keep slide kicking towards the castle till you reach the top
personally i like the way jackocheatie94 mentioned and the luigi way but the one i hate the most is ,you guesseed it, flubber-guts wario.
I HAVE CHANGED MY ACCOUNT TO: SACRED_LIGHT.