I want to mention a few things:
- Do the rules actually specify co-op? I know the recent "triviality of N-player-only games" discussion implies there's some internal judging discussion about this, so maybe it's implied or assumed.
- There's already an existing GB publication that is very explicitly PvP: [5642] GB 4-in-1 Fun Pak: Chess "2 Gameboys" by BlackWinnerYoshi & Spikestuff in 00:15.02
- For GAWG3, 150 stars is probably considered full completion and would require both players anyway. So it becomes a case where some PvP is part of the intentional progression.
For context, the Game & Watch Gallery series has games where the main progression mechanism is stars. You can collect up to five stars in each mode (Classic or Modern)/difficulty (Game A or Game B) combination of each main subgame, generally by reaching 1000 points (200 points per star). When you collect 50 stars in GAWG3, you reach the credits, so that's the standard completion. When you collect
all 150 stars in GAWG3, you get congratulated. 5 of the stars are locked in the multiplayer mode of the Judge B subgame and those happen to be among the faster stars.
To be honest, I don't think a video would impart enough additional clarity to be worth encoding and uploading right now. I'd also prefer not to spoil the new TAS too heavily. Suffice it to say, it would look very similar to the video in
#9128: PiePusher11's GBC Game & Watch Gallery 3 "50 stars" in 38:20.50, but both players play through all the games (technically player 2 has more freedom but still has to collect at least 20 stars to unlock Judge). Judge B is similar to Judge A: most of the optimization comes from RNG manipulation so that the transition between rounds is fast (there's a random speed associated with the foot-tapping and countdown) and so the primary player has a higher number in each round:
https://youtu.be/upNPzKuIDgo?t=1757 -- in Judge B, you can only get maximum points in each round if your number is larger, which is RNG; Judge B also omits the foot-tapping animation and just has the countdown. As far as 2-player visually goes, Judge B is mirrored between both screens, since for the second player, their opponent would be the one scoring. The rest of the run prior could be identical between both players, though for presentation purposes, we might add some variety.
(I can upload a video if you really think it would help, but it might take me some time to get around to it.)