If Neil is a magical girl, he MUST have a final form!
Do you mean like a magical girl outfit transformation? You’re so right. That is the Most Necessary.
When Neil transforms, a shining white light erupts from the flying jorts he wear with him at all times. In his head, he transforms (think typical transformation that slowly moves up his body) by having black tights appear under his short jorts, denim gloves wrap around gracefully along his arm, a denim bow tie appear on the top of his shirt (how does it stick in place? will we ever know?), and a denim mask glides over the top half features of his face.
All in all though, it’s a pretty underwhelming transformation. Neil is too poor or cheap to procure a better costume and he doesn’t really care how he appears, so
It’s amazing none of the Foxes have recognized Neil in his magical girl outfit yet, considering this means that the shirt, shoes, and trademark pair of jorts he wore that day are still very much in place, and Neil only has so many clothes. Not to mention his distinct hairstyle and eye colors.
In other words, Neil is the Kon-El of the magical girl universe. Poor kid is so damn oblivious over how horrible his costume really is.