That's because that guy did something called "porting a character", where he put Marth in 2 slots on that screen, and in 1 of them, he used custom animations. I guarantee that you could rename the Sephiroth to "FitMarth00" and put it in Marth's folder without the .rels or animation .pacs, and it would be a skin over Marth. The icons are still in the same location, whether or not you choose to have the movesets be different. Also, you can use the CSP to make the "CSS Icon". Just copy the CSP, open it up in MS Paint(Literally; though you could do something in GIMP or something, as well), crop it till it's only the head part, move the image to the side temporarily, make an 80x56 green box(You can do this by making a new .bmp, changing the dimensions to 80x56, and then using the color filler tool to make it a very noticable color like lime green or bright red), select ONLY the image that you cropped(Make sure that none of the background in-between the picture and the green box are selected, and that it's only the picture), and then fit the image to that box by unchecking the "Draw Opaque" button, change the attributes to "80" and "56" for the dimensions, and presto! All you have to do is import it into BrawlBox, in the section that I told you earlier about. If you have any questions about how to make the icon, lemme know.