IMO, dry food makes shedding worse. Those "indoor" formulas are lying if they say they can reduce shedding. Dry food doesn't give cats an adequate amount of moisture in their diet, which leads to dry, flaky skin and shedding.
The thing that made the most difference in my cats' coats was switching to all wet/raw, and constant brushing. I really like the Furminator brush, and I also try to wipe them down with a cat safe wet wipe every few days.
To add to the above, supplementing with Omega 3 fatty acids (through fish/krill oil, etc) does a lot to improve skin and fur health and reduce shedding. My guy is on them for allergy symptoms and his fur has never looked better!
Increasing hydration and a basic brushing schedule would be the easiest way, however.