According to the Xbox Store, (thank you Destructiod), Call of Duty: Black Ops 3 will not be getting a season pass on the Xbox 360. The listing on the Xbox Store says the season pass is “not available” on the Xbox 360. The Giant Zombies bonus map isn’t coming to the 360 either.
The map packs will still more than likely come to this years stripped back last-gen version of Call of Duty, just not as part of a season pass. Unfortunately the season pass is unlikely to come to PS3 either, although this has not been confirmed but it’s hard to see Activision offering it to one last-gen console and not the other.
As for the season pass itself, it will come with four map packs and will more than likely be cheaper than buying the packs separately. Black Ops 3 is launching on November 6th across Xbox 360, Xbox One, PS3, PS4, and PC.