Treasure Beach: 15 species in 1 game

15 species, 2 versions

FireRed and LeafGreen

FireRed and LeafGreen: 12 species
Species	Method	Levels	Chance	Game page
Spearow	Walking in tall grass or a cave	31 to 32	30%	All places
Fearow	Walking in tall grass or a cave	36 to 40	20%	All places
Meowth	Walking in tall grass or a cave	31	10%	All places
Persian	Walking in tall grass or a cave	37 to 40	5%	All places
Psyduck	Fishing with a super rod	25 to 35	1%	All places
Psyduck	Walking in tall grass or a cave	31	5%	All places
Tentacool	Surfing	5 to 40	95%	All places
Tentacruel	Surfing	35 to 40	5%	All places
Tangela	Walking in tall grass or a cave	33 to 35	30%	All places
Horsea	Fishing with a good rod	5 to 15	80%	All places
Horsea	Fishing with a super rod	15 to 25	80%	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