Teams are allowed & encouraged! I recommened teams up to 3 or 4.
In terms of creating teams, feel free to create a board on the jam forum and see if people want to collaborate.
So Making an actual Gameboy game if you dont already know is going to way more difficult then just using something like Unity or game maker. There are less resources in terms of documentation and help and it is much more complicated then modern engines.
Ask yourself what it is you want to achieve in the jam - is it to make a cool game? if so, then do that in the easiest, most empowering way and make something really unique
If it is to learn how to make an actual game boy game then great! But you probably wont be able to do that AND make a good game in all likely hood and you would probably do better taking longer then a jam to learn actual hardware.
I hope this helps!
This is unconventional but totally allowed!
As you say, be sure to stick to the right resolution and 4 colour palette.
Also, I wouldn't worry too much about porting it across and instead focus on making a cool game (you can port after the deadline!)
There isnt an official palette per say (even the colours between gameboys themselves were never 100 percent the same) but anything that looks gameboy like is fine.
Feel free to change it up too! The palette I use tends to have a little more blue in there to make it pop.
It wouldn't be allowed as this would generate more then 4 colours but you could fade between different types of dither.
In my game I fade on objects in 4 steps and make sure they fit the colour specs.
You can use existing music as long as it is Gameboy themed and you provide credits and get permission from the artist.
Music from actual Gameboy games is not allowed, as this is a copyright issue.
This is a super interesting question! Generally, I would advise to have the game run full screen but at the correct gameboy ratio and possibly have plain borders BUT I will allow Super gameboy style border graphics as long as it is clear that it isnt part of the game.
Below are examples of this:
However, I would also add that these background must also be four colours (but they can be a different four colours to your game)
Sure! as long as you stick to the colour limitations, that should be fine. If you do end up finding a way to extend te resolution try and do so (or if you share it online, try and add borders if you can). If not - its fine!