Build a BedWars plugin around your own setup: team count, generator tiers, shop items, bed-break rules, respawn. Describe it in English, get a compiled .jar.
Describe your BedWars in plain English: team count, players per team, iron, gold, diamond and emerald generators, shop contents, what breaking a bed does, and how respawn works. Minax writes the Java code, compiles it to a .jar, and you play a round online on a real Paper server before installing it.
You describe the mode in plain English: teams, generators, shop, beds, respawn, commands. Minax writes the Java, compiles it to a .jar and works through compile errors in a self-correction loop. Opening the code afterwards is optional.
Yes, that is the starting point. Write the format you want, such as squads of two or four, and also say what should happen when the queue is not full at the moment the round starts.
Say so in your description if you need it, including how players pick an arena. The wider the scope, the better it works to get one arena playing well first and ask for multi-arena support in a later pass.