Jain meals to my knowledge is available in all Rajdhanis. I always go for jain breakfast as it is made fresh in the pantry.
Do not go by freshness... I used to love the dahiwadas on JNS DR -THVM till I saw them making the wadas ... the wadas are kept in a clean (hopefully) steel dabba and just before serving are squeezed to remove excess water ... If you ever see the process, I can bet you would never dare to eat from train pantries/ catering services again.