Complex sentence: A Sunkern featured in Episode 189, "Moving Picture", in which the group, including Todd, visit a fertile mountain, which has been frozen because of an Articuno, the Pokémon Todd is attempting to photograph.
Split into simpler sentences: A Sunkern featured in Episode 189, "Moving Pictures", in which the group, including Todd, visit a fertile mountain. The mountain has been frozen because of an Articuno, the Pokémon Todd is attempting to photograph.