The Mega Koopa is a Koopa Troopa who obtained a Mega Star. It appears in Super Paper Mario, and one of the heroes has to find a Mega Star for themselves to defeat it. It is found in Chapter 3-1, and you must run away or you will obtain serious damage. Fighting is futile as whichever character you are being is too small to even jump on it. The only way to defeat the Mega Koopa is to grab a Mega Star for yourself. You can get it's card with 100 shop points or rarely in Catch Card Shops.