Who can do it best for India? Let's look at these options from the current squad:
Sehwag- The best bet, talentwise. Also the least useful. With Harbhajan being the top bowler after Kumble (the top bowler period, in ODI's), Sehwag may be one offie too many, unless used properly. He's a very intelligent bowler, and at his slow speed, will be difficult to hit out. His only real problem is his tendency to bowl no-balls and wides, which has reduced. And of course, age isn't on his side. The value he provides is as a second spinner abroad (or even home now), so that the team can pick three seamers and a spinner.
Ganguly- The most relevant of the group. However, also a lot less equipped to deal with the task. He's valuable because if India play four bowlers, they can pick their two spinners, who have over 700 wickets between them, as against three seamers who barely have as much collectively as one of the spinners. His most obvious problem is the stark lack of pace, as well a fitness issues, and also a terrible action- and his all-too-obvious reluctance to bowl- he thinks he's doing the team a big favour, and it shows in his mannerisms, his action and the no-balls and boundary-balls he bowls.
Tendulkar- In the late 90's, he was one of the best leg-spinners the team had, but hardly got a chance. He can turn the ball a great deal, and get a lot of bounce. He's also a handy off-spinner, and when needed, can bowl seam-up. The only problem is lack of practice, leading to lack of focus (explaining as many bowling styles as possible) and lack of consistency- at least two Tendulkar deliveries go over the ropes or into the stands. With injuries plaguing him now, and age not on his side, this bowling arm needs to rest.
Yuvraj- Youngest of the lot. Unfortunately the worst of the lot, and by a long margin. Remember Dimi?
Outside of them, there are options in SRK Vidyut (left-arm spinner for TN, who is also a quick-scoring batting mainstay), Yusuf Pathan (off-spinner who opens the OD batting for his teams), Sanjay Bangar (remember him? possibly the most under-rated cricketer to play for India in the 2000's, post-Robin Singh) and lesser-known contenders such as Rajat Bhatia (slow-medium swing/seam), Abhishek Nayar (sticky seamer), Ravi Jadeja (SLA) and Chandrashekhar Raghu (offie), but we'd be surprised if any of them made India A.