Honestly, You can use whatever art you want. That Pichu that I linked to would be nice, but if you have all the official art then that is fine, They will fit better together, I honestly LOVED that signature so you can try to change the perspective if you want. That was honestly my favorite signature I have ever seen, So if you want to test the perspective look go ahead, I liked the grainy look but again, If you wanna try different things, I can give you honest feedback on it. I am more of a Novice at Photoshop so I really like the look of your peoples signatures and avatars. I do prefer for it to be squares, and I have also tried on MULTIPLE occasions to remake that affect. If you want to you can contact me on Aim(Bajammaz@aim.com)/Gmail(GoGoGengar@gmail.com) for faster responses. If I am not suppose to post those, lemme know.