I made the forum before teams and colors are decided, so we can discuss them here. The rules are the same as in previous 4-player bulldog games, except en passant is allowed, since the change to allow en passant has been made in 4-player chess.
4-Player Bulldog Chess Game

I doubt martin can change the shade, but silver is an inherently darker color if it’s available. I’ll take that.

I doubt martin can change the shade, but silver is an inherently darker color if it’s available. I’ll take that.
Martin made a forum called "Bulldog Chess Templates"
There, it shows all the colours he got
This is a 4-player bulldog with witch and guard game.
Team 1: @PandasAwesome (blue) and @Marks1420 (silver)
Team 2: @rychessmaster1 (red) and @haoming09 (green)
The game will follow the correspondence rules posted here.
Time Control: 3 days/move
Timeout Warnings: 24 hours to make a move after a warning. Maximum 3 warnings. Refreshes every 40th move
Timeout: If a player runs out of time, instead of the team losing the game, a new player can take over, so the game can keep going.
Vacation Time: 14 days. Refreshes every 40th move.
Unrated: This game does not count towards ratings.
Communication: During the game, no consultation except:
Other things, such as move suggestions, telling your plan or warning partner of your opponents threats are not allowed. The players need think for themselves to figure out what their partner is intending to do when they see their partners move.
Move order: The order of moves is clockwise: blue -> red -> silver -> green.
Captures: You cannot capture your teammate's pieces.
Checkmate: Checkmate only happens when a player's turn is reached allowing a player's teammate to intervene. The first team to checkmate an enemy player wins!
Promotion: Pawns promote on the 13th rank and can promote to guard and witch in addition to queen, rook, bishop or knight.
En Passant: En passant is allowed.
Castling: The rules of castling are similar as in classical chess. However the king travels three squares rather than two. The rook finishes adjacent to the king. All squares between the king and rook must be unoccupied, with the exception of transparent pieces (see witch rules).
Setup: See image below
Pieces:
Guard (G) - Moves and captures like a king.
Witch (W) - The rules for the witch can be found here.
Note: Witches make pieces transparent to both yours and your teammates pieces
Other rules of this game are identical with rules of classical chess.
Good luck!