The only appearance of Light Pokémon is in the Neo Destiny expansion, which as the title suggests, revolves around the potential path or "destiny" a Pokémon can follow depending on how it is brought up by their Trainer.
In terms of card design, Light Pokémon have a white-gold character window, evolution box and Pokédex box, as opposed to the regular gold. The card art in many cases depicts the Pokémon seemingly content with itself or in a serene environment. In terms of gameplay, Light Pokémon tend to have higher HPs compared to those of normal Pokémon and attacks that often aid other Pokémon in play, likely due to the caring nature of the Trainer.
Pokémon that have appeared as Light Pokémon
Light Pokémon Cards listed with a blue background are only legal to use in the current Expanded format. Cards listed with a silver background are legal to use in both the current Standard and Expanded formats.