Team Rocket might have hosted repetitive storylines in the original Pokemon anime, but they added a Looney Tunes element to the show that elevated it: plus, the 4Kids English voice team of Jessie, James, and Meowth (Rachael Lillis, Eric Stuart, Maddie Blaustein) was some of the show's finest work. Their colorful presence might be part of Pokemon Go pretty soon, according to dataminer Chrales.
As Chrales points out, a new "Team Rocket Invasion" event is slated to enter the scene, with new badges, "shadow" and "purified" mechanics, and encouragement dialogue from your team leaders (the teams you picked a few years ago and probably forgot about).
Note how I said "might" for the above iconic trio, as so far the datamining efforts entail dialogue from Team Rocket grunts; famous fodder from the games. Go has been reticent about adding too much content from the official series outside of cosmetics, so hopefully The Pokemon Company gives them the chance to go all-out for this one.