I did Onslaught, Hulk, Titania, Ironheart, and Prowler. They were all 7 star rank 3, so it would be more difficult for you. Since you don't have Onslaught, Mr. Sinister should be able to take all of his fights. You really need an evade counter for Spider Ham, Spider Gwen, and Nightcrawler, so Prowler should work for that. I think your team should be Mr. Sinister, Prowler, Hulk, Titania, and another based on what you fights you don't have countered with those champs.
I did Onslaught, Hulk, Titania, Ironheart, and Prowler. They were all 7 star rank 3, so it would be more difficult for you. Since you don't have Onslaught, Mr. Sinister should be able to take all of his fights. You really need an evade counter for Spider Ham, Spider Gwen, and Nightcrawler, so Prowler should work for that. I think your team should be Mr. Sinister, Prowler, Hulk, Titania, and another based on what you fights you don't have countered with those champs. Is it worth taking up Prowler to rank 2 unawakened just for the Ordeal quest? Also heard Chee was a decent option, should I bring her as well?