Can I deduct expenses for my coaching training that included business training for my coaching business?

Yes, if you had an existing coaching business at the time, and paid for continuing education in the way of coaching training, it would be a deductible business expense. If the training occurred prior to starting your coaching business it would not be deductible.  Education expenses to learn a new trade are not deductible.

Where would this be reported? Based on the descriptions of the categories on the 'Enter Your Business Expenses' screen that feeds form 2106, it is not clear which is the best for entering training-related expenses.

Training can be entered under Other Miscellaneous Expenses.