Going to bring back this notable topic.
1. I can agree with the fact that this should display as if playing a multiplayer game, with the other plays' cursors/catchers and whatnot hidden out.
2. The scoreboard for multi can handle more than the maximum displayed on screen. This can be seen in a Taiko game with 7 or 8 players.
3. I am quite neutral with being able to toggle cursors to appear as a ghost replay. It's not necessary, as you can watch the cursor in replay and gather the same information.
4. I believe that the user should be able to highlight scores they want to battle against by clicking on them with the right mouse button. Then when a user has one or more highlighted, a button below the scoreboard will appear saying "Replay Challenge!" This means that this could also apply to the online leaderboard.
5. I believe that the game should collect all the selected replay data into a temporary area to read upon, unless it wouldn't be more taxing to have the replay datas all over the place.
6. The score updates on each note for the other replays in the battle. This would also allow you to battle against a replay using DoubleTime while not using said mod, or battle modless replays while playing in DoubleTime. This would also eliminate the need for using the network utility needlessly and also allows for much cleaner playback. In times where a ghost cursor/catcher is enabled, it will update on every replay frame, like replays normally do, if a toggle for it is added.
7. After the round, you would head into the multiplayer results screen, and you can see the results of each play and the mods used. And below it would of course be the online section, alike singleplayer.