1.
Squirtle = Turtle (duh)
2.
Caterpie = Caterpillar (also duh)
4.
Charmander = Salamander*
7.
Ekans = Snake (E-K-A-N-S = S-N-A-K-E)
11.
Kangaskhan = Kangaroo
12.
Horsea = Seahorse (get it?)
18.
Krabby = Crab (Ohhhhhhhhh)
19.
Exeggutor = This Palm Tree
20.
Snorlax = A Bear Saying Hello
21.
Mewtwo = This Horrible, Disgusting Cat