Stored Power is learned by 18 species by level, 137 by machine and 8 by egg

Effect, in PokéAPI's words

“Power is higher the more the user’s stats have been raised, to a maximum of 31×.”

Who learns it

137 species in all, 8 of 9 games shown

Scarlet and Violet: 108 species

Species	Method	Level
Latias	Level up, Machine	1
Latios	Level up, Machine	1
Indeedee	Level up, Machine	1
Clefairy	Level up, Machine	4
Oranguru	Level up, Machine	15
Chimecho	Level up, Machine	16
Necrozma	Level up, Machine	40
Clefable	Machine, Egg
Ninetales	Machine
Jigglypuff	Machine
Wigglytuff	Machine
Slowpoke	Machine
Slowbro	Machine
Drowzee	Machine
Hypno	Machine
Exeggcute	Machine
Exeggutor	Machine
Chansey	Machine
Eevee	Machine
Vaporeon	Machine
Jolteon	Machine
Flareon	Machine
Mewtwo	Machine
Mew	Machine
Hoothoot	Machine
Noctowl	Machine
Cleffa	Machine
Espeon	Machine
Umbreon	Machine
Slowking	Machine
Misdreavus	Machine
Girafarig	Machine
Dunsparce	Machine
Stantler	Machine
Blissey	Machine
Ralts	Machine
Kirlia	Machine
Gardevoir	Machine
Meditite	Machine
Medicham	Machine
Spoink	Machine
Grumpig	Machine
Jirachi	Machine
Deoxys	Machine
Drifloon	Machine
Drifblim	Machine
Mismagius	Machine
Chingling	Machine
Bronzor	Machine
Bronzong	Machine
Happiny	Machine
Spiritomb	Machine
Leafeon	Machine
Glaceon	Machine
Gallade	Machine
Rotom	Machine
Uxie	Machine
Mesprit	Machine
Azelf	Machine
Cresselia	Machine
Manaphy	Machine
Arceus	Machine
Gothita	Machine
Gothorita	Machine
Gothitelle	Machine
Solosis	Machine
Duosion	Machine
Reuniclus	Machine
Fennekin	Machine
Braixen	Machine
Delphox	Machine
Flabébé	Machine
Floette	Machine
Florges	Machine
Meowstic	Machine
Inkay	Machine
Malamar	Machine
Sylveon	Machine
Klefki	Machine
Diancie	Machine
Primarina	Machine
Ribombee	Machine
Comfey	Machine
Magearna	Machine
Toxtricity	Machine
Sinistea	Machine
Polteageist	Machine
Hatenna	Machine
Hattrem	Machine
Hatterene	Machine
Milcery	Machine
Alcremie	Machine
Calyrex	Machine
Wyrdeer	Machine
Armarouge	Machine
Ceruledge	Machine
Rabsca	Machine
Flittle	Machine
Espathra	Machine
Veluza	Machine
Farigiraf	Machine
Dudunsparce	Machine
Scream Tail	Machine
Flutter Mane	Machine
Iron Valiant	Machine
Munkidori	Machine
Iron Crown	Machine
Terapagos	Machine

Brilliant Diamond and Shining Pearl: 11 species

Species	Method	Level
Clefable	Level up	1
Xatu	Level up	1
Latias	Level up	1
Latios	Level up	1
Clefairy	Level up	4
Natu	Level up	5
Eevee	Egg
Cleffa	Egg
Togepi	Egg
Chimecho	Egg
Chingling	Egg

Sword and Shield: 90 species

Species	Method	Level
Clefable	Level up, Machine	1
Xatu	Level up, Machine	1
Latias	Level up, Machine	1
Latios	Level up, Machine	1
Munna	Level up, Machine	1
Musharna	Level up, Machine	1
Indeedee	Level up, Machine	1
Clefairy	Level up, Machine	4
Natu	Level up, Machine	5
Oranguru	Level up, Machine	15
Victini	Level up, Machine	21
Necrozma	Level up, Machine	40
Ninetales	Machine
Alakazam	Machine
Slowpoke	Machine
Slowbro	Machine
Chansey	Machine
Mr. Mime	Machine
Jynx	Machine
Eevee	Machine
Vaporeon	Machine
Jolteon	Machine
Flareon	Machine
Mewtwo	Machine
Mew	Machine
Hoothoot	Machine
Noctowl	Machine
Cleffa	Machine
Togepi	Machine
Togetic	Machine
Espeon	Machine
Umbreon	Machine
Slowking	Machine
Dunsparce	Machine
Smoochum	Machine
Blissey	Machine
Ralts	Machine
Kirlia	Machine
Gardevoir	Machine
Lunatone	Machine
Solrock	Machine
Claydol	Machine
Jirachi	Machine
Mime Jr.	Machine
Happiny	Machine
Togekiss	Machine
Leafeon	Machine
Glaceon	Machine
Gallade	Machine
Rotom	Machine
Uxie	Machine
Mesprit	Machine
Azelf	Machine
Cresselia	Machine
Woobat	Machine
Swoobat	Machine
Sigilyph	Machine
Gothita	Machine
Gothorita	Machine
Gothitelle	Machine
Solosis	Machine
Duosion	Machine
Reuniclus	Machine
Elgyem	Machine
Beheeyem	Machine
Inkay	Machine
Malamar	Machine
Sylveon	Machine
Klefki	Machine
Diancie	Machine
Primarina	Machine
Comfey	Machine
Tapu Koko	Machine
Tapu Lele	Machine
Tapu Bulu	Machine
Tapu Fini	Machine
Magearna	Machine
Blacephalon	Machine
Dottler	Machine
Orbeetle	Machine
Toxtricity	Machine
Sinistea	Machine
Polteageist	Machine
Hatenna	Machine
Hattrem	Machine
Hatterene	Machine
Mr. Rime	Machine
Milcery	Machine
Alcremie	Machine
Calyrex	Machine

Ultra Sun and Ultra Moon: 21 species

Species	Method	Level
Gardevoir	Level up	1, 58
Gallade	Level up	1, 58
Latias	Level up	10
Latios	Level up	10
Necrozma	Level up	13
Blacephalon	Level up	13
Oranguru	Level up	15
Natu	Level up	17
Xatu	Level up	17
Clefairy	Level up	28
Ralts	Level up	42
Munna	Level up	47
Kirlia	Level up	51
Victini	Level up	89
Eevee	Egg
Cleffa	Egg
Togepi	Egg
Chimecho	Egg
Chingling	Egg
Woobat	Egg
Sigilyph	Egg

Sun and Moon: 20 species

Species	Method	Level
Gardevoir	Level up	1, 58
Gallade	Level up	1, 58
Latias	Level up	10
Latios	Level up	10
Necrozma	Level up	13
Oranguru	Level up	15
Natu	Level up	17
Xatu	Level up	17
Clefairy	Level up	28
Ralts	Level up	42
Munna	Level up	47
Kirlia	Level up	51
Victini	Level up	89
Eevee	Egg
Cleffa	Egg
Togepi	Egg
Chimecho	Egg
Chingling	Egg
Woobat	Egg
Sigilyph	Egg

Omega Ruby and Alpha Sapphire: 18 species

Species	Method	Level
Gardevoir	Level up	1, 58
Gallade	Level up	1, 58
Latias	Level up	10
Latios	Level up	10
Natu	Level up	17
Xatu	Level up	17
Clefairy	Level up	28
Ralts	Level up	42
Munna	Level up	47
Kirlia	Level up	51
Victini	Level up	89
Eevee	Egg
Cleffa	Egg
Togepi	Egg
Chimecho	Egg
Chingling	Egg
Woobat	Egg
Sigilyph	Egg

X and Y: 16 species

Species	Method	Level
Gardevoir	Level up	1, 80
Gallade	Level up	1, 64
Clefairy	Level up	28
Natu	Level up	39
Xatu	Level up	47
Munna	Level up	47
Ralts	Level up	54
Kirlia	Level up	64
Victini	Level up	89
Eevee	Egg
Cleffa	Egg
Togepi	Egg
Chimecho	Egg
Chingling	Egg
Woobat	Egg
Sigilyph	Egg

Black 2 and White 2: 16 species

Species	Method	Level
Clefairy	Level up	28
Natu	Level up	39
Xatu	Level up	47
Munna	Level up	47
Ralts	Level up	54
Kirlia	Level up	64
Gallade	Level up	64
Gardevoir	Level up	80
Victini	Level up	89
Eevee	Egg
Cleffa	Egg
Togepi	Egg
Chimecho	Egg
Chingling	Egg
Woobat	Egg
Sigilyph	Egg