So i know you need 400 to get all the hostages, but how does it work. As in how many trophies do you need to collect before the next hostage pops up? are they in intervals of 20 or what, and that would be how many total hostage missions?

They are not in intervals of 20. You need somewhere around 200 and 300 for two and three, iirc.

I did not need to take all 400 to save all hostages. I had about 365 when

@DonChipotle: oh so there are only like 4 hostages in all and takes about 300 to even get the 3rd one? yesh.

@lusence: There are six. And yes. That is the correct response.

@VictorK: Did you collect Catwoman trophies? Because your Riddler trophy count from the main menu and her count are separate, but both count towards your 400.

There aren't actually 400 trophies in the city and you don't need all of them to find the Riddler. A small amount of the Riddler challenges come from combat, flight, and gadget challenges.

@RockinKemosabe: Do those not count to the 400 total trophies? I've been curious, but just never really tested it, but I have completed all of the physical Riddler challenges.

@SpencerTucksen: I believe they do, he's saying that there are not actually 400 of the actual little trophies scattered.

@SpencerTucksen: I want to say there is at least 350ish physical trophies in the environment and the rest, that equal up to 400, are the other challenges that are about combat, predator, etc., also there are 40 Catwoman challenges, but 36 of them are only trophies.

@xxizzypop: Thank you. It definitely doesn't feel like there are 440 of those damn things. But a lot of them are just ridiculous. Especially the ones with six question marks. Those have been a problem for me.

@RockinKemosabe: Gracias! I'm probably going to need to use Catwoman some more (and her god-awful climbing mechanic) to get some more of those trophies.

@SpencerTucksen: She takes a little to get used to and her whip doesn't work as well as Batman's grapple ability. So getting around the city isn't as easy. Just get most of the trophies as Batman, interrogate Riddler's henchmen and also tag every trophy you come across, including Catwoman's. Makes it a whole hell of a lot easier when you start looking for the trophies.

Also note that some of Catwoman's trophies require Batman's abilities to access. So there will be a wall that needs to be destroyed before Catwoman can enter, etc. Just a heads up.