As far as the forum is concerned, other people's charts are allowed as long as they're anonymized. Birth information must be removed. Name must also be removed, or else replaced with a pseudonym, and if you go the pseudonym route, you must make it clear that it's a pseudonym. To post a non-anonymized chart, you have to have their informed consent.
From an ethical standpoint, astrologers vary on what they're willing to do without the consent and participation of the native. Personally, I do not give chart interpretations on behalf of third parties, whether an actual chart is presented or a mere list of transits. Even if she gave permission, there wouldn't be much I could do without her direct participation, and if she hasn't even given permission, I won't go there at all. But not everyone draws the lines so strictly.
The only time I'm ever willing to use a chart in a reading that does not belong to the querent is when it's the chart of someone they have a personal relationship with and the question deals with that relationship. But in that case, I do not discuss anything about the other person or their chart that isn't directly relevant to their relationship with the querent. "What can they expect from these upcoming transits?" would not be relevant. "These transits are coming to our synastry/composite chart, what might they mean?" could be. But that would require a pre-existing relationship and a good reason on the querent's part for asking.
