Water Spout is learned by 5 species by level and 4 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

9 species in all, 8 of 17 games shown

Scarlet and Violet: 4 species

Species	Method	Level
Kyogre	Level up	90
Squirtle	Egg
Wartortle	Egg
Blastoise	Egg

Brilliant Diamond and Shining Pearl: 5 species

Species	Method	Level
Wailmer	Level up	48
Wailord	Level up	54
Kyogre	Level up	90
Squirtle	Egg
Remoraid	Egg

Sword and Shield: 7 species

Species	Method	Level
Wailmer	Level up	48
Frillish	Level up	48
Wailord	Level up	54
Jellicent	Level up	54
Kyogre	Level up	90
Squirtle	Egg
Remoraid	Egg

Ultra Sun and Ultra Moon: 7 species

Species	Method	Level
Jellicent	Level up	1, 69
Wailmer	Level up	33
Wailord	Level up	33
Frillish	Level up	61
Kyogre	Level up	90
Squirtle	Egg
Remoraid	Egg

Sun and Moon: 7 species

Species	Method	Level
Jellicent	Level up	1, 69
Wailmer	Level up	33
Wailord	Level up	33
Frillish	Level up	61
Kyogre	Level up	90
Squirtle	Egg
Remoraid	Egg

Omega Ruby and Alpha Sapphire: 7 species

Species	Method	Level
Jellicent	Level up	1, 69
Wailord	Level up	33
Wailmer	Level up	41
Frillish	Level up	61
Kyogre	Level up	90
Squirtle	Egg
Remoraid	Egg

X and Y: 7 species

Species	Method	Level
Jellicent	Level up	1, 69
Wailmer	Level up	34
Wailord	Level up	34
Kyogre	Level up	50
Frillish	Level up	61
Squirtle	Egg
Remoraid	Egg

Black 2 and White 2: 7 species

Species	Method	Level
Wailmer	Level up	34
Wailord	Level up	34
Kyogre	Level up	50
Frillish	Level up	61
Jellicent	Level up	69
Squirtle	Egg
Remoraid	Egg