Water Path: 21 species in 1 game

21 species, 2 versions

FireRed and LeafGreen

FireRed and LeafGreen: 15 species
Species	Method	Levels	Chance	Game page
Spearow	Walking in tall grass or a cave	44	20%	All places
Fearow	Walking in tall grass or a cave	48 to 50	15%	All places
Oddish	Walking in tall grass or a cave	44	10%	All places
Gloom	Walking in tall grass or a cave	48	5%	All places
Meowth	Walking in tall grass or a cave	41	10%	All places
Persian	Walking in tall grass or a cave	47 to 50	5%	All places
Psyduck	Fishing with a super rod	25 to 35	1%	All places
Psyduck	Walking in tall grass or a cave	41	5%	All places
Tentacool	Surfing	5 to 40	95%	All places
Tentacruel	Surfing	35 to 40	5%	All places
Horsea	Fishing with a good rod	5 to 15	80%	All places
Horsea	Fishing with a super rod	15 to 25	40%	All places
Seadra	Fishing with a super rod	25 to 35	4%	All places
Magikarp	Fishing with a good rod	5 to 15	20%	All places
Magikarp	Fishing with an old rod	5	100%	All places
Gyarados	Fishing with a super rod	15 to 25	15%	All places
Sentret	Walking in tall grass or a cave	10 to 15	30%	All places
Qwilfish	Fishing with a super rod	15 to 25	40%	All places