In Batman: Arkham City, there are different playable characters that are available with pre-orders. It appears they are either Catwoman, or Robin. I've seen mention of Nightwing, but I think that's for later release.
My question is, do these playable characters have an affect on the main storyline? If I have the Catwoman pack, does that change the main storyline? Or, is it different with Robin? Or, are these just typical extra characters available to use in challenge maps, and things like that?
Best Answer
First off, it's worth mentioning that while Robin is indeed a pre-order bonus character, as detailed in this site (he's a pre-order bonus in BestBuy in the US and GAME in the UK), Catwoman is not a pre-order bonus. Catwoman is only available for people who purchase the game new or pay extra for a key once they buy a used copy. See this article.
Neither effect the main plot directly. Robin is a challenge only character:
And as for Catwoman, it is best to have a look over here:
EDIT: While she does not appear to affect main story, technically, she does change the way the game begins and the amount of Riddler challenges (from here):