Hmm. Somehow I can picture this. Oak:"well here are all of that dear Ash.es pokemon. I sure hope nothing happens to them." daisy:"what is that noise?" *Ground is trembling* Oak:"No...it cant be... ITS TEAM ROCKET! THEY ARE BACK! WITH THEIR ARMY OF RATTATAS!" *epic battle music* But yeah. With all seriousness. I cant imagine team rocket killing ashs pokemon. After all whould giovanni not want ashs strong pokemon? After all giovanni (and possibly other rocket members) know that they are strong. What Im saying is that team rocket was always looking for more strong pokemon and usualy just stole them from their owners. Now that I think of it. Attacking Oaks laboratory would be a pretty good idea. Imagine how many strong pokemon there are. And not just ashes pokemon. There must be another trainers pokemon as well. But I guess it is still possible that some of them would die while there. Like for old age or something. Would be a sad moment for ash to find his old friends dead... :/ (my grammar is horrible at the moment)
Also Known As: Call me what you like. A good nickname is always appriciated. ;D
They'd never die because Pokemon genocide for shock value of all things is a terrible idea, but a focused attack by Team Rocket on Ash's Pokemon would be a pretty interesting mini-arc. His Pokemon are of decent quality, he has a fair amount of them, and Jessie and James can attest to the fact that he's beaten them numerous times so there's definitely some merit there. The biggest problem would be that Ash would have to be in Kanto at the time so he could actually partake in the rescue. Having Team Rocket steal his Pokemon and then bring them anywhere near him would be a bad move on their part.
Chances are he'd just be left with what he has on hand and that wouldn't be a problem except the entirety of Team Rocket would be against him. Maybe there'd be a giant team-up with him and the trainers who most impacted his life throughout his journey. Maybe it'd all make a better movie than a mini-arc. It's a good idea, though.