I just beat the game in Normal difficulty and am currently trying to gather all the Riddler puzzles. If I start a new game to get the Hard Mode Trophy, do I have to re-gather all the Riddler puzzles on that save to get the Platinum (assuming I finish the challenge modes on the Normal save)?
that'd be a no, I say it's better to complete everything on medium as far as riddles and challenges...though with riddles it doesn't matter as difficulty isn't a factor. When completed then do hard...this way you are familiar with what to do and where to go and you know ll of bbatman's combat skills so you can play differently from your 1st time around. So no you will not have to redo riddles and challenges
GamerMoney is right. The only requirement for the Biggest Bang trophy is beating it on Hard, nothing else. The requirements for Perfect Knight is to have a file with 100%, doesn't matter what difficulty. So I would follow GamerMoneys advice and do the Riddler puzzles and challenges on medium, although you can do the riddler puzzles on hard since those aren't any harder to get on the higher difficulties. Only go through hard for the Biggest Bang trophy.
I got this game when it came out and beat it, but i traded it in because i got frustrated with the riddler challenge. It was telling me that i had one more riddler challenge to get but the map for all locations was empty It didnt show me one green question mark, so i didnt know where to look for it. I even got the last riddler challenge, the one that doesnt show up on the map. I got up to 65% of the game completed. I sold it and deleted all my data for it. I purchased the game yesterday and im attempting to beat it on hard. I tried to get another trophy to see to if my trophy data is still ok, but it didnt give the trophy for silent takedowns on a predator challenge. I dont want to beat the game on hard just to find out that it wont give me the trophy. What do yall think i should do.