Thrash is learned by 72 species by level and 27 by egg

Effect, in PokéAPI's words

“Hits every turn for 2-3 turns, then confuses the user.”

Who learns it

95 species in all, 8 of 24 games shown

Scarlet and Violet: 71 species

Species	Method	Level
Whiscash	Level up	Evolve
Eelektross	Level up	1
Mankey	Level up	29
Primeape	Level up	30
Annihilape	Level up	30
Cubchoo	Level up	33
Beartic	Level up	33
Litten	Level up	33
Ting-Lu	Level up	35
Larvitar	Level up	36
Totodile	Level up	37
Sandile	Level up	39
Blitzle	Level up	40
Yungoos	Level up	40
Passimian	Level up	40
Teddiursa	Level up	41
Croconaw	Level up	42
Pupitar	Level up	42
Tyranitar	Level up	42
Brute Bonnet	Level up	42
Doduo	Level up	43
Heracross	Level up	45
Torracat	Level up	45
Komala	Level up	46
Krokorok	Level up	47
Gumshoos	Level up	47
Gyarados	Level up	48
Basculin	Level up	48
Basculegion	Level up	48
Cramorant	Level up	49
Dodrio	Level up	50
Tauros	Level up	50
Feraligatr	Level up	51
Krookodile	Level up	51
Incineroar	Level up	51
Zebstrika	Level up	53
Perrserker	Level up	54
Regieleki	Level up	54
Regidrago	Level up	54
Glastrier	Level up	54
Spectrier	Level up	54
Ursaring	Level up	56
Ursaluna	Level up	56
Morpeko	Level up	60
Piloswine	Level up	65
Mamoswine	Level up	65
Rufflet	Level up	66
Tornadus	Level up	70
Thundurus	Level up	70
Braviary	Level up	72
Eelektrik	Level up	74
Zarude	Level up	78
Slither Wing	Level up	91
Growlithe	Egg
Stantler	Egg
Barboach	Egg
Bagon	Egg
Turtwig	Egg
Grotle	Egg
Torterra	Egg
Cranidos	Egg
Rampardos	Egg
Gible	Egg
Tepig	Egg
Pignite	Egg
Emboar	Egg
Larvesta	Egg
Rockruff	Egg
Arrokuda	Egg
Veluza	Egg
Dondozo	Egg

Brilliant Diamond and Shining Pearl: 35 species

Species	Method	Level
Whiscash	Level up	Evolve, 1
Mankey	Level up	33
Primeape	Level up	35
Larvitar	Level up	36
Totodile	Level up, Egg	41
Pupitar	Level up	42
Tyranitar	Level up	42
Cubone	Level up	44
Heracross	Level up	45
Gyarados	Level up	48
Croconaw	Level up	48
Doduo	Level up	50
Tauros	Level up	50
Teddiursa	Level up	50
Marowak	Level up	54
Spinda	Level up	55
Dodrio	Level up	56
Feraligatr	Level up	58
Ursaring	Level up	58
Piloswine	Level up	65
Mamoswine	Level up	65
Nidoran♂	Egg
Growlithe	Egg
Ponyta	Egg
Lickitung	Egg
Pinsir	Egg
Cyndaquil	Egg
Stantler	Egg
Carvanha	Egg
Wailmer	Egg
Barboach	Egg
Bagon	Egg
Turtwig	Egg
Cranidos	Egg
Gible	Egg

Sword and Shield: 55 species

Species	Method	Level
Whiscash	Level up	Evolve, 1
Cubchoo	Level up	33
Beartic	Level up	33
Litten	Level up	33
Larvitar	Level up	36
Stufful	Level up	36
Sandile	Level up	39
Tyrunt	Level up	40
Passimian	Level up	40
Pupitar	Level up	42
Tyranitar	Level up	42
Archen	Level up	42
Tyrantrum	Level up	42
Bewear	Level up	42
Cubone	Level up	44
Darumaka	Level up	44
Heracross	Level up	45
Torracat	Level up	45
Archeops	Level up	46
Krokorok	Level up	47
Gyarados	Level up	48
Basculin	Level up	48
Cramorant	Level up	49
Tauros	Level up	50
Darmanitan	Level up	50
Krookodile	Level up	51
Incineroar	Level up	51
Marowak	Level up	54
Perrserker	Level up	54
Regieleki	Level up	54
Regidrago	Level up	54
Glastrier	Level up	54
Spectrier	Level up	54
Morpeko	Level up	60
Piloswine	Level up	65
Mamoswine	Level up	65
Guzzlord	Level up	65
Rufflet	Level up	66
Tornadus	Level up	70
Thundurus	Level up	70
Braviary	Level up	72
Zarude	Level up	78
Nidoran♂	Egg
Growlithe	Egg
Ponyta	Egg
Lickitung	Egg
Pinsir	Egg
Carvanha	Egg
Wailmer	Egg
Barboach	Egg
Bagon	Egg
Gible	Egg
Larvesta	Egg
Rockruff	Egg
Arrokuda	Egg

Let's Go Pikachu and Let's Go Eevee: 11 species

Species	Method	Level
Nidoking	Level up	Evolve, 1
Gyarados	Level up	1
Cubone	Level up	30
Marowak	Level up	36
Mankey	Level up	37
Pinsir	Level up	38
Lickitung	Level up	40
Tauros	Level up	42
Doduo	Level up	44
Primeape	Level up	49
Dodrio	Level up	59

Ultra Sun and Ultra Moon: 68 species

Species	Method	Level
Whiscash	Level up	Evolve, 1
Gyarados	Level up	1
Eelektross	Level up	1
Beartic	Level up	1, 59
Braviary	Level up	1, 70
Volcarona	Level up	1
Tornadus	Level up	1, 79
Thundurus	Level up	1, 79
Darumaka	Level up	27
Darmanitan	Level up	27
Larvitar	Level up	28
Pupitar	Level up	28
Tyranitar	Level up	28
Passimian	Level up	29
Cubone	Level up	31
Litten	Level up	32
Mankey	Level up	33
Marowak	Level up	33
Nidoking	Level up	35
Primeape	Level up	35
Torracat	Level up	37
Stufful	Level up	37
Incineroar	Level up	38
Tyrunt	Level up	40
Totodile	Level up, Egg	41
Piloswine	Level up	41
Mamoswine	Level up	41
Basculin	Level up	42
Tyrantrum	Level up	42
Pinsir	Level up	43
Blitzle	Level up	43
Yungoos	Level up	43
Bewear	Level up	43
Sandile	Level up	46
Komala	Level up	46
Guzzlord	Level up	47
Croconaw	Level up	48
Doduo	Level up	50
Teddiursa	Level up	50
Archen	Level up	50
Bouffalant	Level up	50
Gumshoos	Level up	51
Krokorok	Level up	52
Zebstrika	Level up	53
Cubchoo	Level up	53
Tauros	Level up	55
Spinda	Level up	55
Dodrio	Level up	56
Feraligatr	Level up	58
Ursaring	Level up	58
Archeops	Level up	61
Rufflet	Level up	64
Eelektrik	Level up	74
Larvesta	Level up	90
Growlithe	Egg
Ponyta	Egg
Lickitung	Egg
Cyndaquil	Egg
Stantler	Egg
Carvanha	Egg
Wailmer	Egg
Barboach	Egg
Bagon	Egg
Turtwig	Egg
Cranidos	Egg
Gible	Egg
Tepig	Egg
Rockruff	Egg

Sun and Moon: 67 species

Species	Method	Level
Whiscash	Level up	Evolve, 1
Gyarados	Level up	1
Eelektross	Level up	1
Beartic	Level up	1, 59
Braviary	Level up	1, 70
Volcarona	Level up	1
Tornadus	Level up	1, 79
Thundurus	Level up	1, 79
Darumaka	Level up	27
Darmanitan	Level up	27
Larvitar	Level up	28
Pupitar	Level up	28
Tyranitar	Level up	28
Passimian	Level up	29
Cubone	Level up	31
Litten	Level up	32
Mankey	Level up	33
Marowak	Level up	33
Nidoking	Level up	35
Primeape	Level up	35
Torracat	Level up	37
Stufful	Level up	37
Incineroar	Level up	38
Tyrunt	Level up	40
Totodile	Level up, Egg	41
Piloswine	Level up	41
Mamoswine	Level up	41
Basculin	Level up	42
Tyrantrum	Level up	42
Pinsir	Level up	43
Blitzle	Level up	43
Yungoos	Level up	43
Bewear	Level up	43
Sandile	Level up	46
Komala	Level up	46
Guzzlord	Level up	47
Croconaw	Level up	48
Doduo	Level up	50
Tauros	Level up	50
Teddiursa	Level up	50
Archen	Level up	50
Bouffalant	Level up	50
Gumshoos	Level up	51
Krokorok	Level up	52
Zebstrika	Level up	53
Cubchoo	Level up	53
Spinda	Level up	55
Dodrio	Level up	56
Feraligatr	Level up	58
Ursaring	Level up	58
Archeops	Level up	61
Rufflet	Level up	64
Eelektrik	Level up	74
Larvesta	Level up	90
Growlithe	Egg
Ponyta	Egg
Cyndaquil	Egg
Stantler	Egg
Carvanha	Egg
Wailmer	Egg
Barboach	Egg
Bagon	Egg
Turtwig	Egg
Cranidos	Egg
Gible	Egg
Tepig	Egg
Rockruff	Egg

Omega Ruby and Alpha Sapphire: 55 species

Species	Method	Level
Gyarados	Level up	1
Basculin	Level up	1, 56
Eelektross	Level up	1
Beartic	Level up	1, 59
Braviary	Level up	1, 70
Volcarona	Level up	1
Tornadus	Level up	1, 85
Thundurus	Level up	1, 85
Darumaka	Level up	27
Darmanitan	Level up	27
Larvitar	Level up	28
Pupitar	Level up	28
Tyranitar	Level up	28
Cubone	Level up	31
Marowak	Level up	33
Nidoking	Level up	35
Tyrunt	Level up	40
Mankey	Level up	41
Totodile	Level up, Egg	41
Piloswine	Level up	41
Mamoswine	Level up	41
Tyrantrum	Level up	42
Pinsir	Level up	43
Blitzle	Level up	43
Sandile	Level up	46
Primeape	Level up	47
Croconaw	Level up	48
Doduo	Level up	49
Tauros	Level up	50
Teddiursa	Level up	50
Archen	Level up	50
Bouffalant	Level up	50
Krokorok	Level up	52
Zebstrika	Level up	53
Cubchoo	Level up	53
Spinda	Level up	55
Feraligatr	Level up	58
Ursaring	Level up	58
Dodrio	Level up	59
Archeops	Level up	61
Rufflet	Level up	64
Eelektrik	Level up	74
Larvesta	Level up	90
Growlithe	Egg
Ponyta	Egg
Cyndaquil	Egg
Stantler	Egg
Carvanha	Egg
Wailmer	Egg
Barboach	Egg
Bagon	Egg
Turtwig	Egg
Cranidos	Egg
Gible	Egg
Tepig	Egg

X and Y: 55 species

Species	Method	Level
Gyarados	Level up	1
Basculin	Level up	1, 56
Eelektross	Level up	1
Beartic	Level up	1, 59
Braviary	Level up	1, 70
Volcarona	Level up	1
Tornadus	Level up	1, 85
Thundurus	Level up	1, 85
Darumaka	Level up	27
Darmanitan	Level up	27
Larvitar	Level up	28
Pupitar	Level up	28
Tyranitar	Level up	28
Cubone	Level up	31
Marowak	Level up	33
Nidoking	Level up	35
Pinsir	Level up	36
Tyrunt	Level up	40
Mankey	Level up	41
Totodile	Level up, Egg	41
Piloswine	Level up	41
Mamoswine	Level up	41
Tyrantrum	Level up	42
Blitzle	Level up	43
Sandile	Level up	46
Primeape	Level up	47
Croconaw	Level up	48
Doduo	Level up	50
Tauros	Level up	50
Teddiursa	Level up	50
Spinda	Level up	50
Archen	Level up	50
Bouffalant	Level up	50
Krokorok	Level up	52
Zebstrika	Level up	53
Cubchoo	Level up	53
Feraligatr	Level up	58
Ursaring	Level up	58
Dodrio	Level up	60
Archeops	Level up	61
Rufflet	Level up	64
Eelektrik	Level up	74
Larvesta	Level up	90
Growlithe	Egg
Ponyta	Egg
Cyndaquil	Egg
Stantler	Egg
Carvanha	Egg
Wailmer	Egg
Barboach	Egg
Bagon	Egg
Turtwig	Egg
Cranidos	Egg
Gible	Egg
Tepig	Egg

Changed over time

2 changes since Generation I

1. Through Gen IVPower 90120 from Black and White, Generation V
2. Through Gen IVPP 2010 from Black and White, Generation V