Route 28: 20 species in 3 games

Road 28: 20 species across 5 versions

Gold and SilverCrystalHeartGold and SoulSilver

Gold and Silver: 10 species
Species	Method	Levels	Chance	Game page
Poliwag	Fishing with a good rod	20	65%	All places
Poliwag	Fishing with an old rod	10	15%	All places
Poliwag	Fishing with a super rod	40	80%	All places
Poliwag	Surfing	35 to 44	90%	All places
Poliwhirl	Surfing	40 to 44	10%	All places
Ponyta	Walking in tall grass or a cave	40	up to 30%	All places
Rapidash	Walking in tall grass or a cave	42	up to 10%	All places
Doduo	Walking in tall grass or a cave	41	up to 5%	All places
Dodrio	Walking in tall grass or a cave	43	up to 5%	All places
Tangela	Walking in tall grass or a cave	39	up to 30%	All places
Magikarp	Fishing with a good rod	20	35%	All places
Magikarp	Fishing with an old rod	10	85%	All places
Magikarp	Fishing with a super rod	40	20%	All places
Sneasel	Walking in tall grass or a cave	40	10%	All places
Ursaring	Walking in tall grass or a cave	40	up to 20%	All places

Crystal: 10 species
Species	Method	Levels	Chance	Game page
Arbok	Walking in tall grass or a cave	42	up to 10%	All places
Golbat	Walking in tall grass or a cave	40 to 42	30%	All places
Poliwag	Fishing with a good rod	20	65%	All places
Poliwag	Fishing with an old rod	10	15%	All places
Poliwag	Fishing with a super rod	40	80%	All places
Poliwag	Surfing	35 to 44	90%	All places
Poliwhirl	Surfing	40 to 44	10%	All places
Poliwhirl	Walking in tall grass or a cave	40	40%	All places
Ponyta	Walking in tall grass or a cave	40	up to 30%	All places
Rapidash	Walking in tall grass or a cave	40	up to 20%	All places
Doduo	Walking in tall grass or a cave	41	up to 5%	All places
Dodrio	Walking in tall grass or a cave	43	up to 5%	All places
Tangela	Walking in tall grass or a cave	39	up to 30%	All places
Magikarp	Fishing with a good rod	20	35%	All places
Magikarp	Fishing with an old rod	10	85%	All places
Magikarp	Fishing with a super rod	40	20%	All places

HeartGold and SoulSilver: 17 species
Species	Method	Levels	Chance	Game page
Poliwag	Fishing with a good rod	20	60%	All places
Poliwag	Fishing with an old rod	10	15%	All places
Poliwag	Fishing with a super rod	40	80%	All places
Poliwag	Surfing	35 to 40	90%	All places
Poliwhirl	Surfing	40	10%	All places
Ponyta	Walking in tall grass or a cave	40	up to 20%	All places
Rapidash	Walking in tall grass or a cave	41 to 43	up to 10%	All places
Doduo	Walking in tall grass or a cave	41	up to 5%	All places
Dodrio	Walking in tall grass or a cave	43	up to 5%	All places
Tangela	Walking in tall grass or a cave	39	up to 20%	All places
Magikarp	Fishing with a good rod	20	40%	All places
Magikarp	Fishing with an old rod	10	85%	All places
Magikarp	Fishing with a super rod	40	20%	All places
Natu	Headbutting trees	39 to 43	up to 20%	All places
Aipom	Headbutting trees	39 to 43	up to 30%	All places
Heracross	Headbutting trees	39 to 43	up to 50%	All places
Sneasel	Walking in tall grass or a cave	42	10%	All places
Donphan	Walking in tall grass or a cave	40	20%	All places
Linoone	Walking in tall grass or a cave	40	20%	All places
Whismur	Walking in tall grass or a cave	39 to 40	20%	All places
Bidoof	Walking in tall grass or a cave	40	20%	All places
Buizel	Walking in tall grass or a cave	39 to 40	20%	All places