Who or what types of users has the downvote rights to HN submissions?

The short, truthful answer to that question is "no one". The long, incorrect answer is that below are the permissions granted to users after reaching certain thresholds of total upvote points:

* 1 point - unlocks commenting

* 5 points - unlocks submissions

* 10 points - unlocks "ask"

* 50 points - unlocks "show"

* 100 points - unlocks flagging comments

* 500 points - unlocks downvoting comments

* 1000 points - unlocks flagging submissions

* 5000 points - unlocks downvoting submissions

* 10000 points - unlocks editing/deleting your own comments/submissions of any age

* 50000 points - unlocks editing/deleting other people's comments/submissions of any age (i.e. mod status)

* 100000 points - unlocks selection by YC for your startup

Maybe users with enough high karma? I have unlocked a "flag" button recently.

I have 1000+ karma on many of my accounts and all I can downvote is comments that aren't replying to my comments... I guess you already knew that since you have almost 20k karma

I have 1198 and I cannot donwvote submissions