There's 2 of us and whoever is playing as the boss always loses. It seems like after the first attack on the boss it's pretty much endgame. Is there some approach we're missing?

You can switch to DEFENSE mode as the boss by hitting the Zone key to help remove some of your garbage. As well as that, make sure that you're maintaining your attack gague properly and not "wasting" lines by comboing off when the attack is already about to be sent.

what's the zone key? sounds like I have plenty to learn...

Check your controls in the settings. If you're using a keyboard, "A" is the default key.

This wasn't very obvious at all. I didn't know how to clear the attack lines as the boss, so of course I lost.

Originally posted by Simon:

This wasn't very obvious at all. I didn't know how to clear the attack lines as the boss, so of course I lost.

The explanation is in the popup tutorial that appears when you first select the mode (or in the Tutorial section when you re-enter Multiplayer), if people skip through it though there's not a whole lot that can be done.

You need to learn and understand each bosses attacks and how disruptive they are so you have a better idea of when to clear your garbage and when to attack. There is also somewhat of a pattern and somewhat random to which ones are picked, depending on which phase you are on. I know that's vague but it's hard to go over every single boss. Phase in this case means, the more you do boss attacks the more powerful they start to become, but can also take slightly longer to charge up. In higher phases you will do multiple attacks at once.

The most simplistic way to play is 9-0 stack and just do back to back tetrises, switching to defense for one or two tetrises during timed attacks. Keep in mind that different attacks have different effects on players of different skill levels... no next may be worthless against a beginner player because they aren't using their next queue anyway but to a high level player can slow them down quite a bit. Keep an eye on their charge bar, if they're almost filled it's probably better to upstack so you can just start dumping tetrises as soon as their boards connect. Lines you clear as soon as the meter is filled but before the board actually connects will still count towards your defensive. No point in doing some attack that takes 2 or 3 tetrises to charge if they're about to fill their meter anyway.

This is a good starting point https://four.lol/tetris-effect/boss-abilities

I know there's a lot to learn. I don't think I'll ever run out of things to learn in this game. Unfortunately I can't be an effective or competent boss so I always have to play in the team for now.