An Elite Coverup!

On the way to the Grand Festival at Lake Valor, Ash and friends arrive in a small town and run into a young boy who left his Magby at what was apparently a fake Daycare Center. As a result, it was stolen, so Ash and friends decide to help. After they begin their search for Magby, they encounter a woman who introduces herself as Bertha, and who also seems to know how to find Magby. While Ash and Dawn don't see it themselves, Brock realizes who Bertha is. What is Bertha's secret?