I've been trying to go for S ranks with all characters, then I'm gonna try for 1.1 mil, but part of getting good scores is either handling the boss quick and easy (whopper) or holding it 'til the end, now, I'm not a very good player, so I can't survive holding bosses lol, but I also have trouble killing them off quickly so I can focus on killing zombies and J'avo at leisure again. Characters like regular Ada don't seem to have the tools to just obliterate a boss like regular Jake, Sherry or Chris... I know whoppers are easily dispatched with a remote bomb then CDG... But I haven't found any remote bombs in The Catacombs yet, only regular Piers and Leon start out with them, I've been shooting the legs of a whopper as I think it has damage reduction on the body. There's also the beast of many-a-boob that is pretty tough to kill as well... And that instant dying grab... How do you people even boss hold things like that?! You people are machines! The Lepotatsa seems weaker then the Whopper though in terms of overall health though. Another problem I have with is the Gnezdo... Bees thing... This is mainly the case with shotgunners and... Regular Ada/Carla... I'm guessing you could use grenades to take this thing down? That grab can wipe out health FAST though, another J'avo menace is the Napad... Thing can tank hits, would it save time to go behind it and shoot its fleshy area there? Heh, it seems the only boss I don't have a problem with is Strelats (and Ubitvso, but that's due to a lack of trying to quick shot kill in Rail Yard)
tl;dr Strategies for killing pretty much, all the bosses.
If you're playing as Ada, the whoopers die with 3 shots of the regular crossbow arrows. I find that they always come with a small horde of zombies, so kill those off to gain yourself some more combo time if you find that the crossbow is too slow. As for the Gnezdo, use a grenade in order to disperse the swarm, then use a crossbow quickshot UP CLOSE in order to finish off the queen. The quickshot will automatically lock-in to the queen and it's a one hit kill. But if it misses, then just fire a few more since one of them is bound to hit it. I've accidentally killed a few this way just by spamming crossbow quickshots. If you're playing as Carla, then an incendiary grenade or a shot from the grenade launcher should be enough to expose the queen. Use the handgun to finish it off since the aiming is precise.
For the Whopper in Catacombs you can also use a Grenade- there is one in the barrel right on the bridge where it spawns next to the fan- it puts it kneeling position to do a CdG, but since it doesn't do the same damage as a remote bomb, you'll need to finish it w a weapon. Alternatively, there are several hazards by the spawn point (generator, tnt barrel, etc) that a character with a weaker loadout can take advantage of.
Good luck! Feel free to add me!
"Hey! Porky Pig! I hope you get molested!" PSN: TheWorstType