Scope in a fan project is a tricky thing. Normally your scope is determined by budget (your time and money). You are doing this as a hobbyist project, meaning that you aren't working towards a deadline(infinite time) and want to invest as little as possible in the project as you fan financially(almost 0 money). This means that budget has a third unrelated factor which doesn't come up in commercial projects, enthusiasm. You are limited, as a hobbyist, by how much fun you have on a project.
A good rule of thumb is to map out how long you think the project will take, and cater that to how long you WANT to spend on it. Do you plan to crank out an entire region in a year? All that mapping, scripting, modeling, etc? Or will you run or of steam when people don't actively engage with you while developing? Many projects on this forum tend to show to a halt because people don't engage with the creators. Will you be happy working on your project without any community engagement? For how long?
Apologies for any rambling, I'm on mobile which trends to be pretty tedious for writing long posts, but I wanted to weigh in on this as soon as I could.
EDIT: To specifically respond to your post:
Firstly, welcome to the community. It's nice to meet you; I'm Christopher, the surly semi-professional* developer who haunts the forum and likes to offer help where he can.
I had this great concept for a fan-made Pokemon game, in which the gameplay is 3D, and the storyline is a combination of all 6 existing generations.
No. Every 9-year-old dev sees this board and RPG Maker/Unity/Unreal/Game Maker(And others) and plans to do this, and it just becomes a more intensive task with each generation's region introduced. You did not have this idea first.
Does anybody think this is a good idea? I really do, and want to find people who agree with me, so that we can maybe try to put this concept to reality.[/QUOTE]
It's not a great concept. You can't seriously expect to crank out a game with all ~721 Pokemon, all 6 regions. Scope-wise, you're talking about a HUGE balance and design fatigue issue. 8 Gym Leaders + ~24 gym trainers(3 gym trainers/leader) + 8 Gym Puzzles + 5 Pokemon League Encounters * 6 regions. Assuming NO content between these gyms, you're looking at ~270 encounters to balance(I count puzzles because linear gyms are tedious and exhausting).
Why 3D Gameplay? Judging from your post count this is your first project and you've joined for game dev. You have no history of working with any engines, let alone a 3D one over a 2D one. You have no experience(again, as far as I know) in mapping, modeling(assuming you stick with 3D), writing, programming, or even proofreading. Obviously you created this thread to recruit people to your team, but have given no indication that you are capable of executing on anything, so the only recruits you'd get are the ones who are in the same boat as yourself. Try building a small demo of your game idea using any engine first, and you'd prove that you're capable of doing this. I wish you the best of luck, though - if you ever need help with scripting or the like(assuming you're working with Unity or similar), please don't hesitate to ask me; I don't want to join a team, but I'm happy to be consulted and help people to help themselves.
*Formerly a third-year student at DigiPen Institute of Technology, Bachelor of Science in Computer Science and Game Design.