Moon Knight and Colossus are not on the roster of playable characters in the PS2, Xbox, and PSP version. But they can still be accessed on these versions by using an exploit.
Arin Hanson, also known by his alias EgoRaptor, provided the voice for Dr. Bruce Banner in the original release of "Marvel: Ultimate Alliance" after winning a contest held by Activision. However, Hanson's recordings weren't added until the 2016 re-release of he game.
At one point in time, both Link from The Legend of Zelda series and Samus Aran from the Metroid series were playable characters. The reason why both of them were removed is unknown, but it is speculated that it is due to Nintendo being shown the character in a Playstation 2 version of the game, and that they weren't happy with their characters appearing on a competitor's console.