Akshay Kumar =>His movies are already announced for 2019 so he is out of equation for clash.
Salman Khan=> He will come on Eid/Christmas. So he is out of equation for clash.
Shahrukh Khan=> He won't have any release for Jan 2019 and even if he will have it ready he won't have his 2 movies release within span of 30 days. So he is out of equation for clash.
Kangana Ranaut=> She can't afford clash with Hrithik Roshan starer. She is out of equation for clash.
Ajay Devgan => He already have a movie for dec 2018 so it is very unlikely that he will have his movie release in Jan 2019, he will prefer to have some gap between 2 releases. So he is out of the equation.
So among the mentioned option it seems no one will have clash with Hrithik movie.