Yuuka's Assistant Sound

Jack is a recurring character who appeared in the Pokémon anime. He has appeared in eight episodes.

He is a member of Rhonda's Sinnoh Now crew and accompanies her to various assignments. He handles the microphone boom and often drops the boom onto Rhonda's head, which has become a running gag within the series. The reason behind him doing that was not explained, however, though it appears he always does so on accident since he is quick to apologize. However, in Pursuing a Lofty Goal!, Jack fell asleep, which led him to lose his grip on the boom mike. In Beating the Bustle and Hustle!, he dropped it on Jessie's head, and Rhonda threatened to fire him.

Jack's name may come from the TRS connector, also known as the jack.

(Source: Bulbapedia)