Before Red's disappearance, Lorelei and Agatha watched his battle against Bruno. She then reminisced of her first encounter with Agatha, who helped her poisoned Seel at the time by removing the toxins from it with her Gastly at the Power Plant, which Agatha stated that the pollution from the Power Plant caused Seel to be sick.
Years later, it evolved into a Dewgong as Lorelei sent out it out from the edge of a cliff to attack Yellow and Bill. It used Aurora Beam, which circled them and froze the surrounding area where they were standing. She jumped onto her Dewgong and slid her way down to them as they were running away. As they were sliding on the ice, a ridge above them fell on top of them, due to Yellow using Dody to break it off. Once she cleared her head from it, they looke to see where they were, but they disappeared. When a Poké Ball came out from a hole in the ice, she had Dewgong and her Cloyster launch a joint attack, but Yellow managed to pull it back in, as it was attached to a fishing line. When the Poké Ball came back out again, she launched another joint attack, while she was sat on Dewgong. Once she saw that they escaped from behind her, she jumped off Dewgong, but got back on to attack Yellow when they stood in front of each other, while Yellow was on Dody. She attacked, but Yellow, Bill and Dody dodged it while running away again. Lorelei chased them while on Dewgong by having it use Blizzard to move. She then tried to block their way with Ice Beam, but they managed to get away by going into a river. She followed them out into it on her Dewgong.
In a flashback as she was talking to Green, it appeared in the same memory from the day it was poisoned as a Seel.