I am moving to Wuxi and will arrive at Shanghai pudong airport at 6:45 pm.

You can take long-distance bus at the airport. There are buses to take you to the Wuxi Central Bus Station.
According to your arrival time, you can take the bus with the schedule of 19:50 and 20:40.
After arriving at the bus station, do u wanna go to the railway station? If yes, just take a taxi to the railway station.