My take on this:
If there were more than 100 participants at the beginning of the plan year, you have to file a Form 5500. Unless you qualify for an exemption, you will need an accountant's report.
Note: This plan, being new, could not possibly fall under the 80-120 participant rule. You only get out of filing a full 5500 this year if you actually filed a short form last year. With an effective date of 1/1/15, there is no "last year".