Eruption is learned by 7 species by level and 1 by egg

Effect, in PokéAPI's words

“Inflicts more damage when the user has more HP remaining, with a maximum of 150 power.”

Who learns it

7 species in all, 8 of 17 games shown

Scarlet and Violet: 7 species

Species	Method	Level
Typhlosion	Level up	1
Camerupt	Level up	1
Cyndaquil	Level up	64
Torkoal	Level up	64
Quilava	Level up	75
Entei	Level up	78
Groudon	Level up	90

Brilliant Diamond and Shining Pearl: 7 species

Species	Method	Level
Typhlosion	Level up	1, 82
Camerupt	Level up	1, 52
Cyndaquil	Level up	64
Torkoal	Level up, Egg	64
Quilava	Level up	75
Entei	Level up	78
Groudon	Level up	90

Sword and Shield: 3 species

Species	Method	Level
Torkoal	Level up	64
Entei	Level up	78
Groudon	Level up	90

Ultra Sun and Ultra Moon: 7 species

Species	Method	Level
Typhlosion	Level up	1, 82
Entei	Level up	1, 85
Camerupt	Level up	1, 52
Cyndaquil	Level up	64
Quilava	Level up	75
Groudon	Level up	90
Torkoal	Egg

Sun and Moon: 7 species

Species	Method	Level
Typhlosion	Level up	1, 82
Entei	Level up	1, 85
Camerupt	Level up	1, 52
Cyndaquil	Level up	64
Quilava	Level up	75
Groudon	Level up	90
Torkoal	Egg

Omega Ruby and Alpha Sapphire: 7 species

Species	Method	Level
Typhlosion	Level up	1, 74
Entei	Level up	1, 85
Camerupt	Level up	1, 52
Cyndaquil	Level up	58
Quilava	Level up	68
Groudon	Level up	90
Torkoal	Egg

X and Y: 7 species

Species	Method	Level
Typhlosion	Level up	1, 74
Entei	Level up	1, 85
Camerupt	Level up	1, 52
Groudon	Level up	50
Cyndaquil	Level up	58
Quilava	Level up	68
Torkoal	Egg

Black 2 and White 2: 7 species

Species	Method	Level
Groudon	Level up	50
Camerupt	Level up	52
Cyndaquil	Level up	58
Quilava	Level up	68
Typhlosion	Level up	74
Entei	Level up	85
Torkoal	Egg