Current there is no direct train or flight from Wuxi to Yuyao directly, so it is suggested that you transfer at Shanghai. For details:
Firstly, take a bus (2 hours) or an express train (less than 1.5 hours) from Wuxi respectively to Shanghai South Bus Station and Shanghai South Railway Station.

Second, trasfter to a bus or a train at the same station to Yuyao directly in 3.5 hours.

Ps: see the train information at https://www.travelchinaguide.com/china-trains/