My small kids having a playdate with Hasidic family on Shabbat. What can they play or not play?

My family is reform, and I'm not super well versed in some of the more strict stuff that my new friends have. My kids (4M, 2F) made some friends who are Chabad lubivitch/ hasidic. They invited us for a playdate on Saturday and I was gonna bring some things to play, like my daughter has a pretend cash register. But upon a small bit of research it looks like pretend money is a no no, and I'm wondering about the battery operated toys? All kids involved in this play date are under the bar/bat mitzvah age. What should I avoid? Should I just not bring anything?