Talking about official out-station trips, none of the AIIMS institutions send their students on official out-station trips.
AIIMS Jodhpur sends its students to various inter-college fests, for example, Chiasma (AIIMS Bhubaneswar), and Silhouettes (AFMC, Pune), among others. The same goes for other AIIMS institutions.
Regarding the annual freshers’ trip to Shimla, the trip is planned by the Student Welfare Union of AIIMS Delhi. Thus, it is not an official trip and is organized by a student body. AIIMS Delhi has been in place for a very long time and so while other institutions do not have such a tradition in place, the student body at AIIMS Delhi follows it.
Currently, there are a total of 22 AIIMS in the country which are in various stages of operations out of which 9 are fully operational and most of the others have either started the classes or are partially functioning.
In terms of outstation trips neither AIIMS Delhi nor any of the other AIIMS conduct any such activities for their students officially. The Shimla trip done for freshers of AIIMS Delhi is conducted by the Student Welfare Union of AIIMS Delhi which is a student body. Most of the other AIIMS, as you would know, are new institutes and are still in the process of creating such traditions for their students which AIIMS Delhi, being the oldest of them all, already has. So most of them including mine, AIIMS Jodhpur, currently do not have any such outstation trips planned.