According to Article 48(2) of the Agreement on a Unified Patent Court (UPC Agreement), European Patent Attorneys (EPAs) who are entitled to act as a professional representative before the European Patent Office (EPO) pursuant to Article 134 of the European Patent Convention (EPC) may represent parties before the Unified Patent Court (UPC), provided they have appropriate qualifications such as a European Patent Litigation Certificate (EPLC).
The wording of this article suggests that EPAs can prove having suitable qualifications by different means, the EPLC being one of them.