This game is good overall; it has its flaws and bugs, but is still worth booting up every now and then. I've gotta give props to you for actually completing the game, as most fan-projects here (and in general) seem to unfortunately die out after a while. I also admire the variety the player is given access to Pokemon-wise, as well as the backstory and setting.
I haven't beaten the game (currently I'm at rank 7 or 8 I think) so some of these points may not be completely accurate, but here are some things I think have room for improvement:
-The plot leaves much to be desired. You start the game and are literally dropped straight off into the Professor's lab and given a starter, and then told to fight in the colosseum to rank up and access more of the island. And that's really all you do in this game, explore one area of the island to train your team to take on the next rank, then beat it so you can access the next area and do it all over again. It gets kind of old after the first couple of times without some kind of overarching plot to break it up here and there. Even the classic "evil team wants to steal pokemon/take over the region/world/whatever" plot would be a welcome breather from the constant training.
-A good portion of the utility moves don't actually work. Moves like Odor Sleuth and Pain Split always miss where I'm pretty sure they're supposed to work 100% of the time in the mainstream games. Metronome's usefulness, for one, is decreased significantly because of this (I caught a Munchlax in the beach specifically because it had that move only to find out it was kind of a gamble, even more so than it usually is.)
-Some berries don't work either. I had been looking forward throughout the whole game to getting one of those berries that reduce EVs in order to raise friendship, because I wanted to evolve the Munchlax I mentioned earlier. But when I tried to use it, I got the standard "can't use that here" message. Needless to say, this was a massive heartbreaker.
-What is the point of having a rival if they don't do anything? All they do is wait in the arena building and occasionally change up their team. You don't even have to battle them, ever, or at least as far as I've played.
-"I don't sell items to trainers with your rank." It'd be nice to know exactly what rank I need in order to buy things from these shopkeepers, rather than having to check back after every rank-up.
-Spelling and grammar mistakes. Yes, I'm aware that English probably isn't your first language, but it can't be difficult to find a native English-speaker who is willing to simply proofread and perfect the dialogue in the game. This isn't a big issue, since the game can still be understood, but it would be nice to see a non-English fangame translated excellently into English for once (no offense, of course).
Regardless of all the above points, I still love this game and will most likely continue to play it to the end. I just felt like sharing a few things to perhaps increase the quality of the game even further if you decide to continue working on it, and if not, you can use them as tips for future games. Whatever you end up doing, keep up the good work!