Hello Swish.
Im sorry for the inconvenience the user Sliver1232 caused, it seems like the account was created with the purpose to fake bid. Taking this under consideration the bid is invalid and the trade cannot be forced as the user doesnt have any money. Concerning your auction you can either sell the pokemon to the second highest bidder if they still interested or restart the auction if none of the previous bidders dont want to complete the trade, its up to you. The user has been punished for their action. If you have any more question let me know, have a nice day.
Kind regards,
Daredevil