Ah, names, names... I started a thread called Pokémon Violet before discovering that at least two other hacks out there already have the name. Yeesh.
Anyway, interesting concept, but under-developed at best. I like the idea of a game that pits three villain teams against each other. (My general philosophy is "the more Teams, the merrier.") Beyond the concept, though, you'll need a lot more to make this an interesting hack idea. In canon, except for Jessie, James, and Meowth, none of Team Rocket seems to give a care either way about Ash, so I don't know why they'd all be getting revenge on him. Unless you're talking about the main character of the video games? (I usually think of him as Red instead of Ash.) That would make more sense, but still poses some plot problems. When you have, say, the player vs. a huge organization (like in the original games, Red/Ash vs. Team Rocket), there's plenty of playability and it's interesting. However, when you've got the player plus a huge organization vs. a single guy, not only is there not more realism in trying to drag out this rivalry a whole game, but also the player is just one of the masses and not much of an individual.
You'd definitely get more of a plot out of a Rocket-Aqua-Magma rivalry. Still, there isn't much of a reason for Aqua and Magma to be in Kanto. Their goals are, respectively, expanding the seas and expanding the landmass, and the best ways for them to do that is by catching Kyogre and Groudon, neither of which is in Kanto. They don't want to take over the world--or, if they do, they want to take over the world by first controlling its ecology. Why would they come to Kanto and why would their goals conflict with Team Rocket's?
For them to fight, you'll need to find a way for them to come into conflict with each other. For example, maybe the legends people in Hoenn tell about Mew are a little different than those in Kanto, and the people in Hoenn think that Mew has power to change land to water and water to land or something like that; so, Team Rocket might want to catch Mew because of how strong it is, Aqua wants to catch it in hopes that it'll turn land to water for them, and Magma wants it to turn water to land. That's a lame example, but you get the idea.
Anyway, all that aside, kudos to you for trying a Rocket hack, and good luck with it.
