Watt Shop Item Calculation for Pokemon Sw/Sh. Access the app here
First, choose the ball currently being sold by clicking on the ball
Then, choose the first TR currently being sold (the topmost) by entering the name of the move (or part of the name, the app automatically finds a match)
Finally click on "Check" to make sure your selection is valid.
Choose a ball to search and click "Search Ball" if you want to find a ball to buy.
Choose a tr and click "Search TR" if you are looking for a TR.
The result will be displayed at the bottom, including the days to skip, the ball that will be sold on that day and the five TRs that will be sold.