If there are any set rules...I've never heard them. Whatever agreement you come to...that will be it.
I think a good arrangement would be where you give them the images that you take, but you also get to use them for your own portfolio. You may or may not get paid....remember, the experience that you get, may be invaluable to a young or inexperienced photographer.
Some photographers might not want to you have the images because it might reflect poorly on them if someone was to see the same couple/wedding on two different sites (yours and theirs).
Maybe you aren't so much worried about getting experience and you are just selling your skill as a photographer, to the other photographer. In this case, maybe money is a bigger factor.