His Weepinbell was evolved when he left it at the "Day Care" which was actually a scam by Butch and Cassidy to steal Pokemon.
with a leafstone
To get a Victreebel, use a leaf stone on Weepinbell.
Victreebel does not evolve at any specific level because it cannot evolve due to already being a fully evolved Pokémon.
Bellsprout which evolves to Weepinbell then Victreebel (by leaf stone), Bulbusaur which evolves to Ivysaur then Venusaur, Tangela.
You can't catch it in the wild. You'll need to evolve it from Weepinbell with a Leaf Stone.
He captured it since it was a Bellsprout and when he taught it several attacks, it evolved into a Weepinbell. Later, James taught it how to do vine attacks against other Pokemon and it evolved into a Victreebel.
Victreebel is a leaf Pokemon, and its type is Grass-Poison.
Victreebel
You have to use a leaf stone to evolve weepinbell into victreebel.
Victreebel is #71 in the national pokedex, and it is a Grass-Poison type Pokemon.
You have to catch a Bellsprout or a Weepinbell (Evolves from Bellsprout). Then you can use a Leaf Stone on the Weepinbell and it will become a Victreebel.
Victreebel
with a leafstone
the Pokemon is victreebel and you find him in hippowdon temple
To get a Victreebel, use a leaf stone on Weepinbell.
In Pokemon Leaf Green, Exeggcute (into Exeggutor) Gloom (into Vileplume), Weepinbell (into Victreebel)
Victreebel does not evolve at any specific level because it cannot evolve due to already being a fully evolved Pokémon.