In general the best way to watch Western shows in Chinese - assuming you do not have Chinese ID - is to subscribe to Disney Plus, Netflix, Amazon Prime and to a lesser extent Apple TV. They all have a lot of content with Mandarin dubs, although for Netflix you have to go into settings and change your preferred languages for the mandarin options to show up.

I don't think any of them have spongebob currently and my experience is that western VOD sites don't have subtitles.

Your best bet is to Google the show name in Chinese followed by 看. This will give you lots of options to stream.