Response to various birth control pills (diff estrogen / progesterone doses) is a very individual thing. What she should do is work with her doc to find the one that works the best for her. Try one pill, watch for cramping, break thru bleeding (i.e. bleeding mid cycle) huge emotional swings, etc. If it doesn't work, try another one w/ a diff dose of hormones until finding one that works.
I've used "Trilevelin" for about 8 years now with no problem. Ortho Tricyclene is a popular one because they actually advertise that one. Mine was initially selected by my doc - its a very low dose estrogen / progesterone pill - i've had good luck with it. I dont' recall ever noticing any particular increase in weight or anything. I was able to drop down to 8-9% bf naturally (no diuretics, as, etc) for my first comp while on it. My period stopped when I got below 11% bf, but it picked back up again a month after the competition when my bf went back up.
She should work with her doc to get the right dosage. But if it isn't working or is causing some discomfort, she should not hesitate to tell her doc and try a diff one. It may take a few months to get the right one. If she is experiencing serious weight problems, moodiness or discomfort, she should not hesitate to go back to the doc. If he won't work w/ her on it, get a new doc. And in some cases, she may need to look at something besides the pill - e.g. the b/c shot or something.