What level does a Vulpix evolve at?

Vulpix evolves into Ninetales using a Fire Stone.

Vulpix is #37 in the National Pokedex, and was introduced in the Generation I Pokemon titles (Red, Blue, and Yellow) where it could be found (Blue Only) on Routes 7 and 8, and in the Pokemon Mansion, and (Yellow Only) at the Rocket Game Corner. In Generation VI (X and Y), it is unobtainable by encounter. To obtain this pokemon, you must use the Poke Transporter to move it from another game, or trade for it with another pokemon player, since other people have them and breed them.

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If you play LeafGreen, go to Celadon City. In the Celadon Dept. Store on the 4th floor talk to the merchant and buy a fire stone. Give it to Vulpix and you will get Ninetales.