Rototiller is learned by 10 species by level and 6 by egg

Effect, in PokéAPI's words

“Raises the Attack and Special Attack of all Grass Pokémon in battle.”

Who learns it

16 species in all, 4 games

Ultra Sun and Ultra Moon: 16 species

Species	Method	Level
Dugtrio	Level up	1
Linoone	Level up	1
Bibarel	Level up	1
Lopunny	Level up	1
Watchog	Level up	1
Excadrill	Level up	1
Diggersby	Level up	1
Mudsdale	Level up	1, 8
Mudbray	Level up	8
Tapu Bulu	Level up	38
Sandshrew	Egg
Paras	Egg
Onix	Egg
Rhyhorn	Egg
Cacnea	Egg
Dwebble	Egg

Sun and Moon: 16 species

Species	Method	Level
Dugtrio	Level up	1
Linoone	Level up	1
Bibarel	Level up	1
Lopunny	Level up	1
Watchog	Level up	1
Excadrill	Level up	1
Diggersby	Level up	1
Mudsdale	Level up	1, 8
Mudbray	Level up	8
Tapu Bulu	Level up	38
Sandshrew	Egg
Paras	Egg
Onix	Egg
Rhyhorn	Egg
Cacnea	Egg
Dwebble	Egg

Omega Ruby and Alpha Sapphire: 13 species

Species	Method	Level
Dugtrio	Level up	1
Linoone	Level up	1
Bibarel	Level up	1
Lopunny	Level up	1
Watchog	Level up	1
Excadrill	Level up	1
Diggersby	Level up	1
Sandshrew	Egg
Paras	Egg
Onix	Egg
Rhyhorn	Egg
Cacnea	Egg
Dwebble	Egg

X and Y: 13 species

Species	Method	Level
Dugtrio	Level up	1
Linoone	Level up	1
Bibarel	Level up	1
Lopunny	Level up	1
Watchog	Level up	1
Excadrill	Level up	1
Diggersby	Level up	1
Sandshrew	Egg
Paras	Egg
Onix	Egg
Rhyhorn	Egg
Cacnea	Egg
Dwebble	Egg