Hmm!
Mark Darcy- Let's just go ahead and agree forget Bollywood but even in Hollywood no other actor would play Mark Darcy like Colin Firth. Forget Mark Darcy, any Darcy role was just meant for this man and this man only. This is every form Mr. Darcy.
If I HAD to pick someone in Bollywood though I would pick either Vicky Kaushal or Ranveer Singh. SRK or Abhishek if we are doing older cast. Fawad Khan if he was still around. Darcy needs to be a little socially awkward but at the same time quite attractive and dreamy. Not saying people can't find KRK attractive but objectively he is not considered a good looking man in bollywood by most and typically not on women's dream men list.
Bridget Jones- No hot, thin bollywood actress can do this role in my opinion. The whole essence of this role is that this woman is not your typical size 2 hot woman. Yes Priyanka can look like a mess but at the end of the day she is still a hot body putting on frumpy clothing to be unattractive. The way Deepika put on glasses to be the nerd no one supposedly noticed was beautiful in YJHD. So whoever this actress is, she should be able to put on few pounds and act outrageous. For me those would Parineeti, Bhoomi, Radhika Madan, the Dangal ladies . Sonam does a lot of these look at me I am a mess role but she still looks good physically so no.
Daniel Cleaver blah Hugh Grant was born for these types of shallow, womanizer roles. I don't who in Bollywood can do this among younger actors. Ranbir Kapoor, Aditya Roy Kapoor, Siddhart Malhotra, Abhishek Bachchan...