Charles Laughton did not receive an Oscar nomination for portraying Gracchus in Spartacus.
Laughton though is certainly is usually enjoyable self in the role of Gracchus bringing his usual sly manner and wit to the part that is fitting for Gracchus who is constantly playing the politics within Rome to try get what he wants. Laughton makes Gracchus a likable, quietly charming sort, although he effectively inserts the technically unsavory qualities of his character in the usual Laughton style. He is an enjoyable character when he is on screen and his scenes with Ustinov are particularly entertaining as the two play off of each other splendidly.
Laughton is properly believable though in the scenes of the political fighting. Laughton takes the opposite approach to Olivier in that he shows that Gracchus moves to get his way through indirect manner. He does not push his personality on the others rather Laughton shows a far more calm sort of charisma that shows the presence and strength of Gracchus in the political setting well. He creates an interesting contrast with the forceful performance by Olivier, and makes their scenes where they go head to head quite powerful.
This is not quite an incredible performance by Charles Laughton but it is most certainly is a good one. Laughton makes Gracchus a worthy opponent to Olivier's Crassus. He as well creates some of the most entertaining moments in the film through his fun scenes with Ustinov that are work especially well. This is a worthy performance that adds well to his film working well to make the political aspects of the story just as if not more interesting than the slave revolt.