Joy Squad is what they call the entertainment staff. While we found them great at the Grand Luxxe pool with our kids (2 and 4) they were also great at all the other locations in Riviera Maya (Mayan Palace, Grand Mayan, and the Beach Club all have a Joy Squad). We had access to all at the time we went, and they all had pros and cons.
Mayan Palace (on beach by biggest pool) was the largest and had the most activities, but was also the busiest. Beach Club was always empty, and had few amenities for kids, but the most enthusiastic staff (I think they were bored). We often ended up at the Grand Mayan pool even though the Grand Luxxe was available to us, as we liked the shallow entry, and the giant connect 4 game in the shade there.