For Frankie Peanuts in multiplayer, what about using him like a binding contract of sorts? Propose a political deal, external to his ability ("I can destroy [third party]'s Swiftfoot Boots, and in exchange I'd like you to kill the creature wearing them"), then use the ability to ask a question pertaining to the deal ("Will you abide by that arrangement?" or to another player "Will you interfere with that deal?")

The problem is that you are only obligated to do any action if able. “Will you kill the creature if I destroy the equipment?” “Yes.” “Okay, I did my part.” “Sorry, I don’t have a kill spell.”

Could Red have Hexproof based on an ability to "dodge" magic? Most cards dealing with incredible speed are red and we've already seen something like this in Swiftfoot Boots and Lightning Greaves before that.

Red is not defensive in its magic.