Ash and Go meet a Piplup in the Port of Curitilba City. When Ash and Go return to the institute they are contacted by Miss Misaki, the trainer of Piplup.

Here’s a link to the full episode ?

Miss Misaki asks for the whereabouts of Piplup, they soon find out that Piplup has been swimming to the Sinnoh region, Ash and Go head off to find Piplup and return it to Miss Misaki.