Route 27: 31 species in 3 games

Gold and Silver Crystal HeartGold and SoulSilver

Road 27: 31 species across 5 versions

Gold: 16 species
Species	Method	Levels	Chance	Game page
Caterpie	Headbutting a high encounter rate tree	10	50%	All places
Caterpie	Headbutting a low encounter rate tree	10	65%	All places
Caterpie	Headbutting a normal encounter rate tree	10	65%	All places
Metapod	Headbutting a low encounter rate tree	10	15%	All places
Metapod	Headbutting a normal encounter rate tree	10	15%	All places
Butterfree	Headbutting a high encounter rate tree	10	5%	All places
Butterfree	Headbutting a low encounter rate tree	10	5%	All places
Butterfree	Headbutting a normal encounter rate tree	10	5%	All places
Raticate	Walking in tall grass or a cave	28 to 30	up to 40%	All places
Sandslash	Walking in tall grass or a cave	30	up to 5%	All places
Tentacool	Fishing with a good rod	20	35%	All places
Tentacool	Fishing with an old rod	10	15%	All places
Tentacool	Surfing	15 to 24	90%	All places
Tentacruel	Fishing with a super rod	40	20%	All places
Tentacruel	Surfing	20 to 24	10%	All places
Ponyta	Walking in tall grass or a cave	32	up to 5%	All places
Doduo	Walking in tall grass or a cave	28 to 30	up to 50%	All places
Shellder	Fishing with a good rod	20	10%	All places
Shellder	Fishing with a super rod	40	30%	All places
Exeggcute	Headbutting a high encounter rate tree	10	15%	All places
Exeggcute	Headbutting a low encounter rate tree	10	15%	All places
Exeggcute	Headbutting a normal encounter rate tree	10	15%	All places
Magikarp	Fishing with a good rod	20	35%	All places
Magikarp	Fishing with an old rod	10	85%	All places
Chinchou	Fishing with a good rod	20	20%	All places
Chinchou	Fishing with a super rod	40	40%	All places
Lanturn	Fishing with a super rod	40	10%	All places
Quagsire	Walking in tall grass or a cave	28 to 30	up to 50%	All places
Pineco	Headbutting a high encounter rate tree	10	30%	All places

Silver: 17 species
Species	Method	Levels	Chance	Game page
Weedle	Headbutting a high encounter rate tree	10	50%	All places
Weedle	Headbutting a low encounter rate tree	10	65%	All places
Weedle	Headbutting a normal encounter rate tree	10	65%	All places
Kakuna	Headbutting a low encounter rate tree	10	15%	All places
Kakuna	Headbutting a normal encounter rate tree	10	15%	All places
Beedrill	Headbutting a high encounter rate tree	10	5%	All places
Beedrill	Headbutting a low encounter rate tree	10	5%	All places
Beedrill	Headbutting a normal encounter rate tree	10	5%	All places
Raticate	Walking in tall grass or a cave	30	up to 10%	All places
Arbok	Walking in tall grass or a cave	28	up to 30%	All places
Tentacool	Fishing with a good rod	20	35%	All places
Tentacool	Fishing with an old rod	10	15%	All places
Tentacool	Surfing	15 to 24	90%	All places
Tentacruel	Fishing with a super rod	40	20%	All places
Tentacruel	Surfing	20 to 24	10%	All places
Ponyta	Walking in tall grass or a cave	32	up to 5%	All places
Doduo	Walking in tall grass or a cave	28 to 30	up to 50%	All places
Dodrio	Walking in tall grass or a cave	30	up to 5%	All places
Shellder	Fishing with a good rod	20	10%	All places
Shellder	Fishing with a super rod	40	30%	All places
Exeggcute	Headbutting a high encounter rate tree	10	15%	All places
Exeggcute	Headbutting a low encounter rate tree	10	15%	All places
Exeggcute	Headbutting a normal encounter rate tree	10	15%	All places
Magikarp	Fishing with a good rod	20	35%	All places
Magikarp	Fishing with an old rod	10	85%	All places
Chinchou	Fishing with a good rod	20	20%	All places
Chinchou	Fishing with a super rod	40	40%	All places
Lanturn	Fishing with a super rod	40	10%	All places
Quagsire	Walking in tall grass or a cave	28 to 32	up to 55%	All places
Pineco	Headbutting a high encounter rate tree	10	30%	All places

Crystal: 17 species
Species	Method	Levels	Chance	Game page
Raticate	Walking in tall grass or a cave	30	up to 20%	All places
Ekans	Headbutting a low encounter rate tree	10	15%	All places
Ekans	Headbutting a normal encounter rate tree	10	15%	All places
Arbok	Walking in tall grass or a cave	28	up to 30%	All places
Tentacool	Fishing with a good rod	20	35%	All places
Tentacool	Fishing with an old rod	10	15%	All places
Tentacool	Surfing	15 to 24	90%	All places
Tentacruel	Fishing with a super rod	40	20%	All places
Tentacruel	Surfing	20 to 24	10%	All places
Ponyta	Walking in tall grass or a cave	32	up to 5%	All places
Doduo	Walking in tall grass or a cave	28 to 30	up to 40%	All places
Dodrio	Walking in tall grass or a cave	30	up to 5%	All places
Shellder	Fishing with a good rod	20	10%	All places
Shellder	Fishing with a super rod	40	30%	All places
Exeggcute	Headbutting a high encounter rate tree	10	20%	All places
Exeggcute	Headbutting a low encounter rate tree	10	20%	All places
Exeggcute	Headbutting a normal encounter rate tree	10	20%	All places
Magikarp	Fishing with a good rod	20	35%	All places
Magikarp	Fishing with an old rod	10	85%	All places
Hoothoot	Headbutting a high encounter rate tree	10	50%	All places
Hoothoot	Headbutting a low encounter rate tree	10	65%	All places
Hoothoot	Headbutting a normal encounter rate tree	10	65%	All places
Noctowl	Walking in tall grass or a cave	28 to 32	40%	All places
Chinchou	Fishing with a good rod	20	20%	All places
Chinchou	Fishing with a super rod	40	40%	All places
Lanturn	Fishing with a super rod	40	10%	All places
Quagsire	Walking in tall grass or a cave	28 to 30	40%	All places
Pineco	Headbutting a high encounter rate tree	10	30%	All places

HeartGold: 20 species
Species	Method	Levels	Chance	Game page
Raticate	Walking in tall grass or a cave	28 to 30	up to 30%	All places
Sandslash	Walking in tall grass or a cave	30	5%	All places
Tentacool	Fishing with a good rod	20	30%	All places
Tentacool	Fishing with an old rod	10	15%	All places
Tentacool	Surfing	15 to 20	up to 60%	All places
Tentacruel	Fishing with a super rod	40	20%	All places
Tentacruel	Surfing	20	10%	All places
Ponyta	Walking in tall grass or a cave	32	5%	All places
Doduo	Walking in tall grass or a cave	28 to 30	up to 30%	All places
Shellder	Fishing with a good rod	20	10%	All places
Shellder	Fishing with a super rod	40	30%	All places
Exeggcute	Headbutting trees	28 to 32	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
Hoothoot	Headbutting trees	28 to 32	up to 50%	All places
Spinarak	Headbutting trees	31 to 32	30%	All places
Chinchou	Fishing with a good rod	20	20%	All places
Chinchou	Fishing with a super rod	40	40%	All places
Lanturn	Fishing with a super rod	40	10%	All places
Quagsire	Walking in tall grass or a cave	28 to 30	up to 30%	All places
Pineco	Headbutting trees	28 to 29	30%	All places
Linoone	Walking in tall grass or a cave	30	20%	All places
Whismur	Walking in tall grass or a cave	28	20%	All places
Luvdisc	Surfing	20	60%	All places
Bidoof	Walking in tall grass or a cave	30	20%	All places
Buizel	Walking in tall grass or a cave	28	20%	All places

SoulSilver: 21 species
Species	Method	Levels	Chance	Game page
Raticate	Walking in tall grass or a cave	30	up to 20%	All places
Arbok	Walking in tall grass or a cave	28	up to 20%	All places
Tentacool	Fishing with a good rod	20	30%	All places
Tentacool	Fishing with an old rod	10	15%	All places
Tentacool	Surfing	15 to 20	up to 60%	All places
Tentacruel	Fishing with a super rod	40	20%	All places
Tentacruel	Surfing	20	10%	All places
Ponyta	Walking in tall grass or a cave	32	5%	All places
Doduo	Walking in tall grass or a cave	28 to 30	up to 30%	All places
Dodrio	Walking in tall grass or a cave	30	up to 5%	All places
Shellder	Fishing with a good rod	20	10%	All places
Shellder	Fishing with a super rod	40	30%	All places
Exeggcute	Headbutting trees	28 to 32	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
Hoothoot	Headbutting trees	28 to 32	up to 50%	All places
Ledyba	Headbutting trees	31 to 32	30%	All places
Chinchou	Fishing with a good rod	20	20%	All places
Chinchou	Fishing with a super rod	40	40%	All places
Lanturn	Fishing with a super rod	40	10%	All places
Quagsire	Walking in tall grass or a cave	28 to 30	up to 30%	All places
Pineco	Headbutting trees	28 to 29	30%	All places
Linoone	Walking in tall grass or a cave	30	20%	All places
Whismur	Walking in tall grass or a cave	28	20%	All places
Luvdisc	Surfing	20	60%	All places
Bidoof	Walking in tall grass or a cave	30	20%	All places
Buizel	Walking in tall grass or a cave	28	20%	All places