From Delhi, its the report which is mandatory for Dehradun but I would suggest to carry one for Rishikesh too coz you never know. Plus if coming from any other state, Dehradun might ask for the report.
Well well you are traveller and eager to go u than yes especillay for delhities corona test is mandetory and for other states definatly u will be tested on the border by rapid test ,so better to be preapre and from delhi it will cost you maerly 500-800 so all the best