Click h for hammer and j for jump when Mario's turn. Click g for gulp when Yoshi's turn (costs 4 fp) and click p for ground pound when Yoshi's turn. When Macho Grubba is dizzy, he won't attack. The order that you battle is Macho Grubba, Mario, Yoshi. ABILITY: When Yoshi dies, Macho Grubba becomes dizzy for the rest of the time. So, it should be easy.
Credit to Nintendo