That's very easy to do. Just use piercing blow hammer badge.
**UPDATE ????? Defeated**
Yes of course I mean "Doopliss" but that wasn't his name for this battle. Pretty simple, he only got to attack twice and missed both attacks due to multiple close call badges. He has 40 HP and an extra 10...
Did you mean Peril? That's when you get the big attack increase from the Mega Rush badge. I only have the partner version on it right now. And let's just say Goombella with multibonk with that badge has been doing wonders for me.
**UPDATE**
I'm not sure how this happened, maybe because of...
I'll have to get back to you on that. My memory is a bit fuzzy on that. (I haven't beaten that game yet. No spoilers. I really need to play it again >< )
Mario doesn't like it but I get taken all the time. I have caused him a lot of trouble. But it caused him to help so many people. Perhaps its' a good thing I get taken and captured.