1. Dont decrease all the exp of all pokes that have been traded because many players are slack to make his/her own exact exp and many players dont want inexact exp. Instead of decreasing the exp of all pokes, make a room for tax payment. In tax payment, it will include the releasing of pokes.
Example: The tax you should pay from the trade had been made is 26m. Go to the room of tax paying where you could choose the poke you want to use for payment, 25m will be released and the remaining 1m tax, choose again and here will comes the decrease of exp. (I hope you get my point here
If player did not pay his/her tax, give warning and minus points or punishment like temporary ban from trading until he/she paid his/her tax. Give a deadline on paying for the tax, if he/she dont pay by that time, ban from the game. (I guess it is complicated but hoping to workout this way
And
2. Of course, please at least give a minimal increase in exp we will get from Ultimate Trainers. Even I/we know you were doing this for the over exp in the game.
I thank you.
Papa.Gabriel