Wally is a young boy that is stricken with an unknown illness (possibly acute bronchitis, or asthma, based on his symptoms). As the series goes on, Wally slowly becomes healthier and his lungs become stronger, though he still needs to use his respirator suit.

Wally is a caring boy who always puts others before himself and puts trust in his Pokémon. At first, he was frail and weak but after going on his adventure Wally becomes much stronger, more confident in his abilities, and a more powerful Trainer.