Annie and Oakley
In the English version, Annie is the blonde with big spirals of hair (who trains an Espeon), while Oakley has short, blue-silver hair (and trains an Ariados). According to Luis Solis, the woman with the silver hair is Lion, and the other one is Sanna in the Japanese version.
Annie and Oakley are spies for Giovanni who use all kinds of high-tech gadgets to search for Latias and Latios in the canal city of Altomare. Using special glasses, these spies can spot these Legendaries' true forms, even when they're disguised as humans or are camoflaged. Annie and Oakley search for the Soul Dew, a strange crystal that contains the spirit of a Latios (father of the two Legendary Pokemon currently protecting Altomare).
Jessie, James, and Meowth chase after their "co-workers", but they can't keep up with the agile thieves and are soon left behind.
Annie and Oakley are able to capture Latios and steal the Soul Dew, which can be used to power the Defense Mechanism of Altomare - a strange contraption that grants the user immense power. Oakley uses the Defense Mechanism to resurrect the fossils of Aerodactyl and Kabutops (the real Pokemon, not MissingNo!) and seal off the city from outsiders in an attempt to capture Latias.
After Ash and friends (with the help of Latias and Latios) shut down the Defense Mechanism, Annie and Oakley are trapped inside the control pod until the police arrive. During the 5th movie's closing credits, we see the fate of the pair of thieves - they appear to be researching new items to steal We soon notice, however, that they're currently in prison and not likely to be stealing any time soon.
Of the two, Annie seems to be more concerned with her appearance and "shiny things" than anything else. Oakley, on the other hand, has a taste for power and being in control, and goes megalomaniacal when she operates the Defense Mechanism.