I love Sunqua fractal!
My normal team consists of my wife, daughters (9 & 11), and niece (17). It took us a few hours to learn the fight. We eventually beat it though, with everyone standing. The cheers and pride I saw on my daughters' faces for persevering were great. Bosses should be hard and there should be a challenge. Learning patterns, working together, and thinking of new ways to be successful is what makes games fun.