Hey,
I am inclined to agree with many of the earlier posts on a few matters. With so many people always attempting Pokemon games, why not just take the idea of monster collection and make it your own... There are plenty of alternatives in the real commercial world, so why not give it a shot yourself. There is also Digimon, Monster Rancher, Monster Hunter, to name but a few.
Why not keep all the idea's you enjoy about Pokemon, and then place them into a fresh idea that is original to you. I personally really like the pirate theme, there aren't many sea based adventures around for rmxp, so why not take full advantage of that. It would give your game a clear distinction between this and other pokemon fan games. It will still appeal to Pokemon fans, but also be a breath of fresh air at the same time.
I like the monsters already added. If altorn keeps making them, then they should look great.
You could use this as an opportunity to add darker elements to the game, which go hand in hand with piracy. A deeper storyline, a moodier atmosphere at times, the loss of a few pokemon cliches.
Of course, if a pokemon specific game is what you really want to do then great! I'm just adding to previous posts about how you can keep the good/pokemon elements, but make something totally fresh, and without being restricted to ONLY adding Pokemon things and NOT being able to add your own elements. I'd love to see more monster catching games, but why not make youe every own pirate themed game around it!
Good luck on this anyway!