Wish is learned by 18 species by level and 24 by egg

Effect, in PokéAPI's words

“User will recover half its max HP at the end of the next turn.”

Who learns it

42 species in all, 8 of 17 games shown

Scarlet and Violet: 28 species

Species	Method	Level
Jirachi	Level up	1
Florges	Level up	1
Luvdisc	Level up	13
Flabébé	Level up	20
Floette	Level up	20
Illumise	Level up	22
Gardevoir	Level up	28
Flutter Mane	Level up	28
Latias	Level up	30
Alomomola	Level up	37
Scream Tail	Level up	70
Clefairy	Egg
Clefable	Egg
Eevee	Egg
Pichu	Egg
Cleffa	Egg
Igglybuff	Egg
Girafarig	Egg
Plusle	Egg
Minun	Egg
Chimecho	Egg
Chingling	Egg
Fennekin	Egg
Braixen	Egg
Delphox	Egg
Komala	Egg
Pawmi	Egg
Fidough	Egg

Brilliant Diamond and Shining Pearl: 21 species

Species	Method	Level
Jirachi	Level up	1
Togekiss	Level up	1
Illumise	Level up	22
Gardevoir	Level up	28
Latias	Level up	30
Natu	Level up	40
Xatu	Level up	48
Togepi	Level up	52
Togetic	Level up	52
Eevee	Egg
Pichu	Egg
Cleffa	Egg
Igglybuff	Egg
Girafarig	Egg
Smoochum	Egg
Skitty	Egg
Plusle	Egg
Minun	Egg
Spinda	Egg
Chimecho	Egg
Chingling	Egg

Sword and Shield: 19 species

Species	Method	Level
Jirachi	Level up	1
Togekiss	Level up	1
Gardevoir	Level up	28
Latias	Level up	30
Swirlix	Level up	30
Slurpuff	Level up	30
Natu	Level up	40
Xatu	Level up	48
Togepi	Level up	52
Togetic	Level up	52
Eevee	Egg
Pichu	Egg
Cleffa	Egg
Igglybuff	Egg
Smoochum	Egg
Pidove	Egg
Audino	Egg
Spritzee	Egg
Togedemaru	Egg

Ultra Sun and Ultra Moon: 32 species

Species	Method	Level
Latias	Level up	1
Jirachi	Level up	1
Florges	Level up	1
Gardevoir	Level up	14
Flabébé	Level up	20
Floette	Level up	20
Illumise	Level up	22
Natu	Level up	28
Togepi	Level up	29
Togetic	Level up	29
Xatu	Level up	29
Alomomola	Level up	37
Swirlix	Level up	45
Slurpuff	Level up	45
Eevee	Egg
Pichu	Egg
Cleffa	Egg
Igglybuff	Egg
Girafarig	Egg
Smoochum	Egg
Skitty	Egg
Plusle	Egg
Minun	Egg
Spinda	Egg
Chimecho	Egg
Chingling	Egg
Pidove	Egg
Audino	Egg
Fennekin	Egg
Spritzee	Egg
Komala	Egg
Togedemaru	Egg

Sun and Moon: 32 species

Species	Method	Level
Latias	Level up	1
Jirachi	Level up	1
Florges	Level up	1
Gardevoir	Level up	14
Flabébé	Level up	20
Floette	Level up	20
Illumise	Level up	22
Natu	Level up	28
Togepi	Level up	29
Togetic	Level up	29
Xatu	Level up	29
Alomomola	Level up	37
Swirlix	Level up	45
Slurpuff	Level up	45
Eevee	Egg
Pichu	Egg
Cleffa	Egg
Igglybuff	Egg
Girafarig	Egg
Smoochum	Egg
Skitty	Egg
Plusle	Egg
Minun	Egg
Spinda	Egg
Chimecho	Egg
Chingling	Egg
Pidove	Egg
Audino	Egg
Fennekin	Egg
Spritzee	Egg
Komala	Egg
Togedemaru	Egg

Omega Ruby and Alpha Sapphire: 30 species

Species	Method	Level
Latias	Level up	1
Jirachi	Level up	1
Florges	Level up	1
Gardevoir	Level up	14
Flabébé	Level up	20
Floette	Level up	20
Illumise	Level up	22
Natu	Level up	28
Togepi	Level up	29
Togetic	Level up	29
Xatu	Level up	29
Alomomola	Level up	37
Swirlix	Level up	45
Slurpuff	Level up	45
Eevee	Egg
Pichu	Egg
Cleffa	Egg
Igglybuff	Egg
Girafarig	Egg
Smoochum	Egg
Skitty	Egg
Plusle	Egg
Minun	Egg
Spinda	Egg
Chimecho	Egg
Chingling	Egg
Pidove	Egg
Audino	Egg
Fennekin	Egg
Spritzee	Egg

X and Y: 30 species

Species	Method	Level
Jirachi	Level up	1
Florges	Level up	1
Latias	Level up	5
Gardevoir	Level up	17
Flabébé	Level up	20
Floette	Level up	20
Illumise	Level up	21
Natu	Level up	28
Togepi	Level up	29
Togetic	Level up	29
Xatu	Level up	30
Alomomola	Level up	37
Swirlix	Level up	45
Slurpuff	Level up	45
Eevee	Egg
Pichu	Egg
Cleffa	Egg
Igglybuff	Egg
Girafarig	Egg
Smoochum	Egg
Skitty	Egg
Plusle	Egg
Minun	Egg
Spinda	Egg
Chimecho	Egg
Chingling	Egg
Pidove	Egg
Audino	Egg
Fennekin	Egg
Spritzee	Egg

Black 2 and White 2: 23 species

Species	Method	Level
Jirachi	Level up	1
Latias	Level up	5
Gardevoir	Level up	17
Illumise	Level up	21
Natu	Level up	28
Togepi	Level up	29
Togetic	Level up	29
Xatu	Level up	30
Alomomola	Level up	37
Eevee	Egg
Pichu	Egg
Cleffa	Egg
Igglybuff	Egg
Girafarig	Egg
Smoochum	Egg
Skitty	Egg
Plusle	Egg
Minun	Egg
Spinda	Egg
Chimecho	Egg
Chingling	Egg
Pidove	Egg
Audino	Egg