I'd hate to be overly blunt, but if you have to ask others for a plot, chances are you're going to have a
lot of problems down the line. After all, a lot of creativity goes into writing, so if you can't come up with a general idea for what you want to do, you'll probably end up getting stuck when you try to execute the more detailed version of that same idea.
This is because a story often has subplots that go right along with it. The concept -- what most people call the plot -- is just a very general overview. For example, if you have a concept wherein these Pokémon go on a Mystery Dungeon-like adventure to defeat (insert evil Pokémon here), that's fine, but beyond that, you might have subplots involving them falling in love with each other, them trying to get used to their powers, all kinds of other things. You're going to have to come up with those yourself because, well, we can't really be there for you all the time to write the story yourself. Not to mention it'd be much more satisfying to you if you came up with your own idea and to us to read your creativity at work.
With that being said, my advice is, if you're suffering from a lot of writer's block, to do any number of the following:
1. Look hard at your characters. You've already got a halfway decent plot as it is. Kids get turned into Pokémon. They don't know why. They set out on a journey to figure it out. Just add the reason and maybe (if applicable) some antagonists, and you've got yourself the skeleton of a story.
2. Think about what you want to write about. Yes, what you
want to write about. Another reason why we can't give you a plot? Because not everything floats everyone's boats. For example, I hate writing sappy romance a la some romantic comedy film, but I love writing dark fic. If someone asked me to write sappy romance, I'd go for about two pages before someone gets bound and tortured. Short of it is, ask yourself what kinds of genres you're most interested in. Are you more of a fantasy person? Science fiction? Do you like happy endings or sad ones? Things like that. (No, I'm not expecting an answer to any of these. Do not answer these questions to get me to come up with a plot for you.)
3. Tied in with the above, read, watch some TV or movie, listen to music, do a lot of other things that are in the same genres as what you want to write about. That should give your brain a jumpstart in order to think of potential ideas.
4. Read a lot of fanfiction too. Fanfics on this forum are also sorted by genre in
the Fanfiction Index. You can use that as a tool to guide yourself to your genre(s) of interest.
5. Open up a blank word processor document or your notebook and write down notes. They can be anything from backstories and more information about your characters to whatever pops into your mind first. Getting the thoughts from your head to someplace where you can see them and go back over them can help you keep track of your ideas as well as add to them later. Something might pop up the longer you go about doing this.
6. When you've got a general concept or few, take it here and put it up. In the Plot Bunny Thread, you can get feedback on your thoughts as well as a few nudges in the right direction. However, remember. Don't go there until you come up with a general idea
first.
Tl;dr, sorry to say, but it's a good idea to sit down and push yourself to think of a plot instead of asking others to do it for you. You can, though, if you work hard enough on it. Good luck!