I think it's a TM or maybe something between lv.15 and lv.30
Diglett evolves into Dugtrio at Level 26.
Dragonair does not learn Dragon Rush in Pokemon Leafgreen. However, it can learn the move in Pokemon Diamond, Pearl and Platinum at level 39.
Diglett evolves into Dugtrio, starting at level 26.
I think 73
Charmeleon learns Flamethrower at level 34.
In Pokemon FireRed and LeafGreen, Diglett can learn Dig at level 17, which is a nice and early level for a good move.
Diglett evolves into Dugtrio at Level 26.
Dragonair does not learn Dragon Rush in Pokemon Leafgreen. However, it can learn the move in Pokemon Diamond, Pearl and Platinum at level 39.
Diglett evolves at Level 26.
In Pokémon LeafGreen, Geodude will learn Magnitude at Level 16.
Diglett evolves into Dugtrio, starting at level 26.
It learns slash at level 28 I think
I think 73
Ivysaur will learn sweet scent at level 29 in Pokemon fire red and left green.
Diglett evolves into Dugtrio at level 26.
It learns Swagger at level 61.
It learns Solarbeam at level 43. It can also learn Solarbeam by TM, which you get at the Pokemon Mansion.