Question

Is ranger the only touchscreen game?

Comments

I assume you mean where the primary gameplay is done through the Touchscreen and you are unable to substitute with the buttons?

Answer 1

No, there's also Pokemon Dash. It was the first Pokemon game for the DS so it really took advantage of the touch screen feature.
Some of the DS Mystery Dungeon games have things you can do with the touch screen, but mostly for mini-games.