Crimsonwood 2

That's really annoying to have a PQ where you NEED to have a certain class though. There's ways to make classes useful without making them needed.

-Make monsters elementally weak, that'll instantly help pallys/mages.
Making them elementally weak doesn't really do anything, it lets mages/pallys do more damage but doesn't really give them a good reason to take them. Any other of the overpowered classes can really take out any monsters. Would only be usefull if they make it so that an elemental attack is needed other than holy, which would leave bishops out of it and take AM/pallys. And the weapon attack classes should do 1 dmg at this stage.
-Make the boss summon hords of mobs. Great time for ultimate mob control
Again the most wanted, Bishops can easily replace any other ultimate spammers.
-Give the monster a high kickback rate (25k+) and high touch damage. That'll make classes that hit hard in one shot needed to keep a boss knocked back (pallys, mages, pallys, bucs, shadowers) to keep him away from the ranged.
Put a few NLs with SE and apple and they can do the job just as well and faster. NLs with this combination can hit numbers that shadowers and mages have no chance in... at the same time they take out the boss much faster with the insane damage... so who do you think people will take more?
-Let him do physical defense up only instead of physical and magic. Once again, good for mages
The other most wanted classes can easily just spent the time chatting around just like zak/ht or anyother boss that cast physical def up.

Seriously, it doesn't take a rocket scientist to make everyone useful.

Even if you make some of these other classes a little usefull, the most wanted classes can do better job of it still with given buffs which still gives the unwanted classes a really hard time finding parties. Really making them a little usefull doesn't change from anything we have now. The easiest way to go about it is to make these classes a must to take or something like stereo mentioned "Would be neat if you just got +10 seconds of bonus for every class, so the best party (13 subclasses incl. 90+ beginner) got 130 seconds in the bonus stage, while the more typical NL+BM+Bishop+DK would only get 40 seconds, but be easier to form"

I can't see nexon doing anything different this time, it'll be just as same as its always been, just like GPQ. Bishops easily replacing the arch mages, NLs replacing Shadowers, DrK and Heros replacing Pallys.