Pick one DC or Marvel then bring a character(s) from anywhere and put it in the one you picked. You can pick anime, video games, and etc. Pick characters that you would think would make the comics even more enjoyable
My pick Marvel
Master Chief - well technically his in marvel but it would be cool to see him in the 616 universe. A good mid power superhuman who i think could fill a captain america spot as in leader in some kind of avengers league
Vegeta, Broli, Metalic Cooler- Some DBZ guys who would be cool to fight vs some of the High Herald level type characters. Vegeta in particular I really like where broli and cooler are just cool guys to throw in a fight. Vegeta actually is the only 3 dimensional character from DBZ and it would be nice to see how marvel would write him.
Superman- Well what can I say I am not his biggest fan except the JLU version. It would be nice to see him go against Sentry and Hulk and even have team ups. I didnt really care for the comics but I though it was a cool picture when supes had Mjolnir and Cap america's shield
Flash- Hes better then quicksilver and has a good sense of humor. I would replace quicksilver with him
GL corpse- It would be cool to see the GL corpse deal with some of the Marvel galactic threats like Galactus and Thanos