بسم الله الرحمن الرحيم
In case there is no Imam available and there is no other abler person who could lead the salah then you may lead the salah. In common situation salah in pant and shirt is makrooh tahrimi, and in case of compulsion it is allowable.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.