I don't have nearly as much experience with Roy as I do with Ike, but I'd give it dead even. Both have a good number of kill moves and good combo game, especially off of grabs. Roy is certainly more mobile than Ike and has an easier time landing thanks to his fall speed and Nair, but that same quality means his recovery is hot garbage and he can't edgeguard as well when he plummets like a rock offstage. Meanwhile, Ike both has greater reach and is mostly able to inflict consistent, heavy damage no matter where an enemy is within his attack range, but he has no real answers to getting juggled, usually can't attempt more than one attack per jump, and his smashes are much more unwieldy. Both are capable of going ham on opponents but neither are really capable of forcing an opening due to leaving themselves open if they don't space well. Ike has more kill options, but Roy's Blazer gives him an OoS kill option Ike doesn't have.