Anything is acceptable, you can stipulate pairings, or not. You can request xovers. You can lay out detailed scenarios. You can just say UNICORNS! and that's fine, we all know what a unicorn is.
Leave the prompts in the comments and claims prompts as replies. Multiple people can share prompts as polyamory is encouraged.
YOU DO NOT HAVE TO COMMIT TO WRITING TO LEAVE A PROMPT. Every/anyone can leave a prompt.
Come early and come often. ~ James T. Kirk