Though PMU7 is not released yet, I can foresee scammers i.e:
Trade:
You: 250000 poke
Other Person: Earthquake
You: 250000 poke, Accepted
Other Person: EarthPLATE, Accepted
Looks like you just got scammed for a earthplate.
An easier way to fix this is just to add a new window:
You are trading 250000 poke for Earthplate
There is NO way to reverse the trade
[Accept] [Decline]
By noticing that the item is changed, you decline the offer