You started a thread with this same statement, but I will just respond to that here.
Took me a bit to track down what a Deoxys is, then to find its "speed form." Bah, I apparently am getting old. Just feel lucky I haven't started telling ya darn kids ta get off my lawn, dagnabit.
Anywho, I can see a similarity in the general shape (a VERY general shape), mostly in the lack of a nose, the things on the side of its head, and the unreasonably long arms... and the fact that they are both in an anime-like style (is it still anime if it is from a video game?). Calling it a casual similarity, however, would be going too far. Deoxys also has a bit of a facial similarity with ol Faceless Redrum, the main differences there being the eyes and skin color.