Bulbasaur #001

Ivysaur #002

Venusaur #003

Charmander #004

Charmeleon #005

Charizard #006

Squirtle #007

Wartortle #008

Blastoise #009

Caterpie #010

caterpillar an insect (chenille)
Metapod #011

Butterfree #012

Weedle #013

Kakuna #014

cocoon a pupal casing made by some insects
Beedrill #015

Pidgey #016

pigeon a species of bird
Pidgeotto #017

pigeon a species of bird
Pidgeot #018

pigeon a species of bird
Rattata #019

Raticate #020

Spearow #021

Fearow #022

Ekans #023

snake a species of reptile; ‘ekans’ spelled backwards is ‘snake’
Arbok #024

cobra a type of snake; ‘arbok’ spelled backwards is ‘kobra’