Warning! There is a strong opinion contained in this post that may not be suitable for anyone who cannot handle honest thoughts from the universe at large. Be warned.
So, in other words, it's exactly like all of the other stories about fledgling Trainers with a name that isn't even real who go on another Average Ordinary Everyday Life-Changing, World-Saving Journey, except this
time Team Galactic want to take control of a ridiculous amount of Legendaries that will probably do nothing to further their goals and just make it that much more obvious that they are, indeed, villains?
Uhh... let's start from the top. Notes in bold...
Okay I'm planning on making a fan fiction called Pokemon pearl destiny.
It's about a boy named Fecback (I'm a girl in real life (So?)) (I made that name up (Stop here. I would like to take this time to redirect you to Behind the Name, a lovely website which has an extensive database of first names. It's better than making one up that sounds like it belongs to a werewolf in Harry Potter.)
cause I decided I wanted to be a boy in my pearl and and be a girl in my diamond (So what? Why does this help us at all?))
It's based on Pokemon pearl (Clearly, seeing as it's called Pearl Destiny - which is an extremely overused name, by the way. Maybe try thinking up something better?)
and how team galactic wants to control the world (I thought they wanted to blow it up? You have your evil teams messed up... Team Rocket wants to control the world.)
however instead of just palkia there is also dialga arceus shaymin giritina mesprit uxie azelf cresselia & others. (I've never heard of a Dialgaarceusshaymingiritinamesprituxieazelfcressel iaandothers... what is that Pokemon again?)
His rival jun is trying to beat him to everything. (No surprises there.)
I will make him beat cynthia (You'll make him beat cynthia? I didn't see that coming at all! And goodness, how cruel of you to make your character do something...)
I'm sure then it will end a long time from now... (No, it won't. You'll give up quite early in, I bet.)
Unless you want me to add.... The sinnoh battle frontier to make it Pearl Platinum fic! (Uh... what?)
Should I or should I not?
Is this a good idea?
There was nothing in that paragraph that made me want to read your fic more than just start over my copy of Diamond and follow the exact same plot. I strongly suggest you scrap this 'idea' (it isn't even your idea) and ty to think of something more original and interesting.