Leafusaur

Summary
Leafusaur is the evolved form of Eeveesaur. It is a fusion of Leafeon and Venusaur.

How to get it and what it evolves into
If you choose Bulbasaur as your starter and evolve it, you can fuse the Eevee and the Ivysaur in Bill's house to get Eeveesaur and then evolve it to Leafusaur.