Instead of Frieza, I would pick Future Trunks. It would set up really great interactions and I think it would be cool to see him work alongside his father Vegeta, his mentor Gohan and the androids. I'd also try to utilize the full potential of other fighters from different universes so it's not always Universe 7 taking the spotlight. I'd be sure to allow Krillin, Tien and Roshi to last longer than they did in the anime. What are your thoughts?