Does 16 years old soccer players should go to the embassy in person to submit China visa application?

I am bringing 14, 15 and 16 year old soccer players to the china great wall cup on July 15. I understand the 14 and 15 years old need not personally appear so does it mean the travel agent may get visas for them? The 16 year olds and adult coaches should personally go to the embassy with their documents?or Do they need to get an appointment before going to the embassy?
If so, how do they get an appointment?

For the non first timers and with previous sticker visas, may ask travel agent to process visas for them? Thank you