Walkthrough
After defeating the Elite Four, you can also find Jessie and James, the former members of the now disbanded Team Rocket, on Route 17. They will question to each other what will happen to Team Rocket now, mentioning how Giovanni is currently in hiding while planning his next scheme. When they notice your trainer, they will challenge you to one last battle. Once defeated, they will again offer you the chance to join Team Rocket. They will accept your refusal, but will give you a Team Rocket Uniform before they depart, just in case you ever change your mind.
Level 52 Arbok: Poison Jab, Glare, Crunch, Rock Slide
Level 52 Weezing: Sludge Bomb, Dark Pulse, Flamethrower, Thunderbolt