One Piece thread (Spoilers)

So pile'o'pomegranate.
And for that matter, how would they even know what the effects of knocking her out would be?

Op tends not to leave any loose ends, itll most likely be elaborated after/during the battle. It could be assumed the gnome spies acquired this information. But by your logic, luffy, would not be rubber when he's asleep which is not true. Or when Lucci was finally beaten he didn't revert to his form, while kaku did.

Either it would have happened before (Then why wasn't there already a massive revolt against doflamingo?), the knowledge of the particular devils fruit is public (No-one could possibly work out that the one town with an army of living toy workers is the one where the very specific power is at) or they're making it up based on nothing.

Or the gnomes overheard don flamingo explaining why she can't sleep while shes whining, possibly be the reason she eats grape, we won't know until it's explained to us, and OP's pretty consistent on that regard.