Yes, Shahrukh Khan has conditions before once can sign him for a film. According to reports, his contract has two conditions:
1) He will not do any lip-locking scenes with actress (and we have never seen him do that)
2) He will not ride horses.
The latter seems to be a bit odd, after all, we have all seen him riding horses in 90's films such as Karan-Arjun, Baazigar. This condition is because he has developed a back problem with age and the kind of work that he does, he just cannot be galloping around anymore.