Why did you change the canon pokemon of most characters?
I didn't replace the canon Pokemon of most characters. In fact, most of them (but not all) still have their entire two or three Pokemon team from the vanilla games, along with some of the Pokemon they use in Pokemon Special. Off the top of my head, a few examples of this include Viola, Grant, Korrina, Serena/Calem, Siebold and Lysandre. Diantha's team was mostly replaced because it wasn't very good, and was mostly made of Pokemon already used by Gym Leaders.
For example Ramos is supposed to have a Weepingbell (Victrebell), Jumpluff and Gogoat, yet even in legal you replaced two of those with more of the same overused pokemon,
Victreebel would have been redundant alongside Mega Venusaur, which was the only fitting mega evolution for Ramos. I suppose Jumpluff could have been used instead of Whimsicott, though. Other replacements were made simply to take advantage of access to the entire national dex, which improves enemy Pokemon variety.
even with the same movesets everyone has.
Now this one is a good point, but what would you suggest instead? I'd love to see a few examples, if you have time. The movesets I've used are generally simple ones because the AI can't figure out more interesting gimmicks. It doesn't even understand most of the abilities added after gen IV, and struggles to use most complex moves effectively.
You did the same to every single trainer.
Again, no, I didn't. Most trainers kept at least one of their default Pokemon, and plenty of them have silly, gimmicky movesets, or no custom movesets at all.
This doesn't feel like canon XY at all
Honestly, I got the same feeling from some of the battles while playing this. Unfortunately, as XY never got a third version and doesn't really do anything with its gym leaders in the post game, there wasn't much to work with when choosing Pokemon for their teams. Additionally, canon XY was pathetically easy, which I was trying to avoid repeating with this hack.
and now we have to fight all those overused gimmicks that we constantly fight on multiplayer battles even in a singleplayer game.
You missed the point completely.
No? I may have missed your point, but as you had zero involvement in creating this hack, that's not really a problem. I made the hack I wanted to make. You're welcome to edit it or make your own if you have a different vision for what an XY hack should be.