Destiny Bond is learned by 27 species by level and 21 by egg

Effect, in PokéAPI's words

“If the user faints this turn, the target automatically will, too.”

Who learns it

46 species in all, 8 of 19 games shown

Scarlet and Violet: 34 species

Species	Method	Level
Cacturne	Level up	1
Froslass	Level up	1
Hoopa	Level up	1
Pecharunt	Level up	16
Drifloon	Level up	32
Drifblim	Level up	36
Gastly	Level up	44
Vespiquen	Level up	44
Phantump	Level up	48
Trevenant	Level up	48
Koffing	Level up	52
Haunter	Level up	54
Gengar	Level up	54
Cacnea	Level up	54
Dusknoir	Level up	54
Qwilfish	Level up	56
Overqwil	Level up	56
Weezing	Level up	62
Iron Valiant	Level up	77
Giratina	Level up	84
Misdreavus	Egg
Delibird	Egg
Houndour	Egg
Ralts	Egg
Gulpin	Egg
Shuppet	Egg
Spiritomb	Egg
Inkay	Egg
Malamar	Egg
Sandygast	Egg
Mimikyu	Egg
Charcadet	Egg
Maschiff	Egg
Greavard	Egg

Brilliant Diamond and Shining Pearl: 25 species

Species	Method	Level
Wobbuffet	Level up	Evolve, 1
Cacturne	Level up	1, 59
Wynaut	Level up	1
Froslass	Level up	1
Drifloon	Level up, Egg	32
Drifblim	Level up	36
Gastly	Level up	44
Vespiquen	Level up	44
Koffing	Level up, Egg	52
Haunter	Level up	54
Gengar	Level up	54
Cacnea	Level up	54
Dusknoir	Level up	54
Weezing	Level up	62
Qwilfish	Level up	66
Giratina	Level up	84
Misdreavus	Egg
Delibird	Egg
Houndour	Egg
Ralts	Egg
Gulpin	Egg
Carvanha	Egg
Shuppet	Egg
Duskull	Egg
Spiritomb	Egg

Sword and Shield: 31 species

Species	Method	Level
Wobbuffet	Level up	Evolve, 1
Wynaut	Level up	1
Froslass	Level up	1
Drifloon	Level up	32
Drifblim	Level up	36
Gastly	Level up	44
Vespiquen	Level up	44
Frillish	Level up	44
Jellicent	Level up	48
Phantump	Level up	48
Trevenant	Level up	48
Koffing	Level up	52
Yamask	Level up	52
Haunter	Level up	54
Gengar	Level up	54
Dusknoir	Level up	54
Weezing	Level up	62
Cofagrigus	Level up	62
Runerigus	Level up	62
Qwilfish	Level up	66
Giratina	Level up	84
Delibird	Egg
Ralts	Egg
Carvanha	Egg
Spiritomb	Egg
Elgyem	Egg
Honedge	Egg
Inkay	Egg
Pumpkaboo	Egg
Sandygast	Egg
Mimikyu	Egg

Ultra Sun and Ultra Moon: 33 species

Species	Method	Level
Wobbuffet	Level up	1
Qwilfish	Level up	1, 53
Cacturne	Level up	1, 59
Vespiquen	Level up	1, 53
Froslass	Level up	1, 61
Hoopa	Level up	1
Wynaut	Level up	15
Giratina	Level up	24
Phantump	Level up	39
Trevenant	Level up	39
Gastly	Level up	40
Koffing	Level up, Egg	40
Weezing	Level up	46
Yamask	Level up	49
Haunter	Level up	50
Gengar	Level up	50
Cacnea	Level up	54
Cofagrigus	Level up	57
Misdreavus	Egg
Delibird	Egg
Houndour	Egg
Ralts	Egg
Gulpin	Egg
Carvanha	Egg
Shuppet	Egg
Duskull	Egg
Drifloon	Egg
Spiritomb	Egg
Honedge	Egg
Inkay	Egg
Pumpkaboo	Egg
Sandygast	Egg
Mimikyu	Egg

Sun and Moon: 33 species

Species	Method	Level
Wobbuffet	Level up	1
Qwilfish	Level up	1, 53
Cacturne	Level up	1, 59
Vespiquen	Level up	1, 53
Froslass	Level up	1, 61
Hoopa	Level up	1
Wynaut	Level up	15
Giratina	Level up	24
Phantump	Level up	39
Trevenant	Level up	39
Gastly	Level up	40
Koffing	Level up, Egg	40
Weezing	Level up	46
Yamask	Level up	49
Haunter	Level up	50
Gengar	Level up	50
Cacnea	Level up	54
Cofagrigus	Level up	57
Misdreavus	Egg
Delibird	Egg
Houndour	Egg
Ralts	Egg
Gulpin	Egg
Carvanha	Egg
Shuppet	Egg
Duskull	Egg
Drifloon	Egg
Spiritomb	Egg
Honedge	Egg
Inkay	Egg
Pumpkaboo	Egg
Sandygast	Egg
Mimikyu	Egg

Omega Ruby and Alpha Sapphire: 31 species

Species	Method	Level
Wobbuffet	Level up	1
Qwilfish	Level up	1, 53
Cacturne	Level up	1, 59
Vespiquen	Level up	1, 53
Froslass	Level up	1, 61
Hoopa	Level up	1
Wynaut	Level up	15
Giratina	Level up	24
Phantump	Level up	39
Trevenant	Level up	39
Gastly	Level up	40
Koffing	Level up, Egg	40
Weezing	Level up	46
Yamask	Level up	49
Haunter	Level up	50
Gengar	Level up	50
Cacnea	Level up	54
Cofagrigus	Level up	57
Misdreavus	Egg
Delibird	Egg
Houndour	Egg
Ralts	Egg
Gulpin	Egg
Carvanha	Egg
Shuppet	Egg
Duskull	Egg
Drifloon	Egg
Spiritomb	Egg
Honedge	Egg
Inkay	Egg
Pumpkaboo	Egg

X and Y: 31 species

Species	Method	Level
Wobbuffet	Level up	1
Qwilfish	Level up	1, 53
Cacturne	Level up	1, 71
Vespiquen	Level up	1, 53
Froslass	Level up	1, 59
Hoopa	Level up	1
Wynaut	Level up	15
Giratina	Level up	24
Phantump	Level up	39
Trevenant	Level up	39
Gastly	Level up	40
Koffing	Level up, Egg	40
Weezing	Level up	46
Yamask	Level up	49
Haunter	Level up	50
Gengar	Level up	50
Cacnea	Level up	57
Cofagrigus	Level up	57
Misdreavus	Egg
Delibird	Egg
Houndour	Egg
Ralts	Egg
Gulpin	Egg
Carvanha	Egg
Shuppet	Egg
Duskull	Egg
Drifloon	Egg
Spiritomb	Egg
Honedge	Egg
Inkay	Egg
Pumpkaboo	Egg

Black 2 and White 2: 22 species

Species	Method	Level
Wobbuffet	Level up	1
Wynaut	Level up	15
Giratina	Level up	24
Gastly	Level up	40
Koffing	Level up, Egg	40
Weezing	Level up	46
Yamask	Level up	49
Haunter	Level up	50
Gengar	Level up	50
Qwilfish	Level up	53
Vespiquen	Level up	53
Cacnea	Level up	57
Cofagrigus	Level up	57
Froslass	Level up	59
Cacturne	Level up	71
Misdreavus	Egg
Ralts	Egg
Gulpin	Egg
Shuppet	Egg
Duskull	Egg
Drifloon	Egg
Spiritomb	Egg