Considering we still have cards like Emboar (Ability and Bad), Magnezone, and Reshiram, I don't think it being broken will be a problem.
How did I make the Lv.X card? I have a font guide for what fonts to use, the placement of the fonts, things like that, so all I did was take a Lv.X blank (made by cascadegonpory, used with permission), pasted it on to the font guide, edit the text, add the picture, and the Lv.X was made.