This case study reports on a co-creation initiative that explored the use of generative artificial intelligence (AI) technologies in the context of higher education assessments. The AI Co-Creators project aimed to promote dialogue between students and staff on the impact of AI with the objective of using AI tools more effectively. The case study presents a collaborative partnership which focused on evaluating ChatGPT-generated output in response to diverse coursework assessments on an undergraduate medical sciences programme. The co-design of evaluation criteria and key findings are presented and resultant challenges faced by students and staff are explored through dialogue, interview, and thematic analysis. The value of the student-staff collaboration is explored from the perspective of the student, staff, and institution, while the benefits, limitations and recommendations for future co-creation projects are presented in the context of AI and higher education assessment and learning.