From Bulbapedia, the community-driven Pokémon encyclopedia.
Viridian Forest (Japanese: トキワのもり Tokiwa Forest) is a location in Pokémon Channel. It can be visited by traveling on the bus once the Viridian Pass has been obtained from the shopping channel.
A campfire is held every non-rainy night. After Jirachi arrives with the projector, the Pichu Bros. episode can be watched in the stars on clear nights. It is also possible to stargaze on clear nights.
Camp Starlight on Tuesday night
The campfire can only be visited at night, and only if it is cloudy or clear. The weather does not affect the Pokémon that appear.