simple upload it to a website (or in a php loader like Xampp's localhost) and test it out there and report any problems : D (remember to copy the url and paste it into the trade script)
Everything in the list (numbers, names, caught icon, presumably your icons as well) is positioned in the def drawItem in class Window_Pokedex. However, the area in which these things are visible is defined by the line @sprites["pokedex"]=Window_Pokedex.new(blahblablah) further down.
Shift the area to the left a bit, then in drawItem move the text to the right by the same amount, to keep it in the same place. This will give you more space on the left of the list to put your Pokémon icons in.