Madragore, Melaqua, Pumpyro and Elecmon

Mandragore (Eevee+Oddish): They bury themselves deep in the ground in search of nutrition and for the stones which it can use to evolve. It is said that removing a Mandragore from its burrow will make it shriek so loud it can cause deafness.
 
Water Stone - Melaqua (Vaporeon+Oddish): They have an incredible thirst and refuse to leave water areas. One Melaqua can drink over 10 litres of water per day. They can learn several water attacks, as well as others such as Bullet Seed.
 
Fire Stone - Pumpyro (Flareon+Oddish): It is said that a flame is used for each of their vital organs. Their body heat is extremely high for a plant, its breath alone can cause 2nd degree burns. Since their first encounter in the dark by a group of tourist, the Pumpyro have become a great Halloween mascott.
 
Thunder Stone - Elemon {spelled "Ele" as in electric and "mon" as in Lemon } (Jolteon+Oddish): The strangest of the three, the meter on their chest mark the remaining energy in them. If you think their Thunder Bolt was fatal, Elemon can even use acid attack