I recommend pokémon too, fire red for gba or White and Black for nds. beautiful and enjoyable art style/sound track, a lot of legends to read and understand (it isn’t dubbed), he will need to train and manage their pokémons to use the correct one for each battle or challenge, explore, learn and practice their skills.
pokemon games are very beautiful and fun, this one looks simple but is full of adventure.

Zelda is amazing too, Ocarina of Time is great.