Bulbasaur #1

Ivysaur #2

Venusaur #3

Episode Numbers, and Pokemon Numbers won't match up for Squirtle and Charmander Stages. 

Squirtle #4

Wartortle #5

Blastoise #6

Charmander #7

Charmeleon #8

Charizard #9

Caterpie #10

Metapod #11

Butterfree #12

Weedle #13

Kakuna #14

Beedrill #15

Pidgey #16

Pidgeotto #17

Pidgeot #18

#19 #19Rattata #20Raticate

#20 #21Spearow #22Fearow

#21 #23Ekans and #24Arbok

#22 (later baby form)Pichu #25Pikachu and #26Raichu

#23 #27Sandshrew and #28Sandslash

#24 #29Nidoran(F)#30Nidorina and #31Nidoqueen

#25 #32Nidoran(M)#33Nidorino and #34Nidoking

#26 (Later Baby Form) #35 #36

Ep#27 #37 #38

Ep#28 (Later Baby Form)#39 #40

Ep#29 #41 #42 (Later Form Added)