That’s right they manage to make sprites for those Pokemon in this ROM hack of Crystal. Pokemon Prism features over 250 Pokemon from Generation I until IV. Now, you must find the mystery surrounding this world while becoming a Pokemon Master. You are in the Naljo Region, where you discover a lost Larvitar and become its master.
You play as the child of Lance, who is the Pokemon Champion in Crystal. Pokemon Prism is a hack of Pokemon Crystal, and the story is probably taken from it.