In RB and therefore FR/LG, Lv3 Electrode by catching a Lv3 Pikachu, evolving it and then doing the in-game trade for Electrode. On a related note, Red/Blue's rival battle in the Pokemon Tower, where he somehow has a Hydro Pump Gyarados at around Lv22.
Redpebbles, I seriously doubt the rival will change his team, with the possible exception of evolving his Magneton and Sneasel. As for your comment on the rival's parents, 1. There's no real reason for Giovanni to find a girl from Team Rocket, and 2.
You're not the first person to joke about Mars (around 6:40 in the video).