The badge's effects stack if multiple copies of it are equipped, possibly even rendering Mario's defense power below 0 if enough are equipped. (mariowiki.com)
One mod that was supposed to boost my attack and defense power when playing alone didn't seem like it was very effective. (thekoalition.com)
These Talisman can have up to three slots as well as bonus effects such as defense power, support boosts, and more. (dailydot.com)