I took Eevee and Flareon, put Eevee's head on Flareon, and and put Eevee colors on Flareon's Body.
Suggested by: Pika Ana
So just keep putting suggestions in the comments.
i suggest using one of the original eevee sprites, and then taking something from all the other eeveelution sprites, and adding it to the eevee sprite, that's my piece of advice