Eeveesaur

Eeveesaur is a Grass and Poison-type Pokémon Fusion. It is a fusion of Ivysaur and Eevee.

It evolves into Leafusaur at Level 32.

Eeveesaur can be obtained if the player chose Bulbasaur as a starter by evolving it and then fusing Ivysaur with Bill's Eevee upon meeting him at Sea Cottage.

Rival's Eeveesaur
If the player's Rival, Brendan or May, chooses Bulbasaur as his or her starter, he or she will fuse it into Eeveesaur, presumably with Bill's help. He/she will first use it when encountered on Route 6. When encountered in Pallet Town, it's evolved into Leafusaur.

Other Eeveesaur
Picnicker Tina of Celadon Gym will use an Eeveesaur which was created by Bill.

A trader named Eva in Ecruteak City will trade the player an Eeveesaur in exchange for a Meganium if the player does not own one already.

Pokédex Entry
"Its animal instincts are heightened, but its plant-like qualities have diminished. Its flower is beginning to wither."

Locations

 * Sea Cottage (Fuse Ivysaur with Eevee)
 * Ecruteak City (Trade for Meganium)

Trivia

 * Eeveesaur was created in 2012 and its sprite was updated to the current one in 2013.
 * This makes it the last Eevee Fusion created. Charvee, Warvee, Pikavee, and Growlvee were all made in 2005.
 * It's also the first to be completely redesigned after Pokémon Fusion Generation was released. The original version was featured in earlier versions of the game, in the game trailer, and its silhouette appeared on the original title screen.
 * Being an Eevee Fusion, it's one of only five Pokémon Fusions that can evolve in Pokémon Fusion Generation, the others being Charvee, Warvee, Pikavee, and Growlvee.