"options that depend on options" should not be a thing. Every option should be optional. Even if you have working code that can handle some complex situation, this doesn't make the situation any less unintuitive for the users.
If you need more complex relationships, consider using arguments as well. Top level, or under an option. Yes, they are not named, but since they are mandatory anyway, you are likely to remember their meaning (spaced repetition and all that). They can still be optional (if they come last). Sometimes an argument may need to have multiple parts, like user@host:port You can still parse it instead of validating, if you want.
> mutually exclusive --json, --xml, --yaml.
Use something like -t TYPE instead, where TYPE can be one of json, xml, or yaml. (Make illegal states unrepresentable.)
> debug: optional(option("--debug")),
Again, I believe it's called "option" because it's meant to be optional already.
optional(optional(option("--common-sense")))