you can only get false swipe in the d/p series. in
emerald,sceptile learns it at lv 59. i dont have any other
The only (capturable without trading) Pokémon that can learn False Swipe in Emerald are Sceptile, Nincada, and Zangoose.
Sceptile learns it at level 59. If you chose Treecko as starter, train it until it's evolved into Sceptile and then up to level 59.
Nincada learns it at level 25. (Keep it from evolving via giving it an Everstone or pressing B whenever it wants to evolve until then).
Zangoose learns it at level 55.
I know that nincada learns it after the level it is supposed to evolve, so keep it from evolving at it should learn it quickly. as for a TM, I do not think there is one.