I'm sure there will be at least one pro-corporate braindead reject who'll tell you to buy another copy of Ranger, but no, you're not cheating.Would it be legal to delete a game's save file using an external device?
More specifically, I found out that starting a new game on Pokémon Rnager: Shadows of Almia and saving doesn't erase the Ranger Net data, used for the missions which give you downloadable Pokémon. Instead, I borrowed my brother's flash cart and erased the entire save file that way.
So, is this frowned upon or not? It's hard to tell, since it's a lot different from how D/P work... In my opinion, it's just like restarting D/P to get the legends again.