Empoleon was originally meant to be a second electric type Eeveelution early on in development. Evidence for this can be seen in the use of the -eon suffix (something all Eeveelutions use) and the first three letters of its name being EMP (meaning Electromagnetic Pulse)
This was obviously scrapped and GameFreak decided to design it with the Napoleon motif that final Empoleon uses instead because, coincidentally, it's name was already similar to "Napoleon".