That's up to you hon, and your own levels. Generally speaking, if they're asking for GG then it's likely they'll require some interaction between the models. Though it's dangerous to generalise! If you've seen an ad asking for GG why not contact them and ask for clarification?
Ask the photographer. You might feel silly at first but tbh it's always best to ask - Think about how silly you'd feel if you got it wrong and turned up to someone expecting you to do more than you're willing. Better to ask than end up with a reputation as a time waster for turning up to something you won't do.