Pokémon League: 8 species in 2 games

Sinnoh League: 8 species across 3 versions

Diamond and PearlPlatinum

Diamond and Pearl: 7 species
Species	Method	Levels	Chance	Game page
Tentacruel	Surfing	35 to 45	35%	All places
Magikarp	Fishing with a good rod	10 to 25	55%	All places
Magikarp	Fishing with an old rod	3 to 10	100%	All places
Gyarados	Fishing with a super rod	30 to 40	40%	All places
Remoraid	Fishing with a good rod	10 to 25	45%	All places
Octillery	Fishing with a super rod	20 to 50	45%	All places
Pelipper	Surfing	35 to 45	65%	All places
Luvdisc	Fishing with a super rod	20 to 30	15%	All places

Platinum: 8 species
Species	Method	Levels	Chance	Game page
Tentacruel	Surfing	30 to 50	5%	All places
Magikarp	Fishing with a good rod	10 to 25	55%	All places
Magikarp	Fishing with an old rod	3 to 15	100%	All places
Gyarados	Fishing with a super rod	30 to 55	40%	All places
Remoraid	Fishing with a good rod	10 to 25	45%	All places
Octillery	Fishing with a super rod	30 to 55	45%	All places
Wingull	Surfing	30 to 40	60%	All places
Pelipper	Surfing	30 to 50	35%	All places
Luvdisc	Fishing with a super rod	20 to 30	15%	All places