Research capability is broader than one certificate. It can be shown through an honours thesis, master's thesis, research methodology training, publications, conference papers, research employment, professional reports, laboratory experience, fieldwork, data analysis, creative research outputs or other evidence relevant to the discipline.
A strong applicant should organize this evidence clearly. If the CV says the applicant has research experience, the documents should support it. If the proposal depends on advanced methods, the transcript, thesis or work history should make those methods believable.
For PhD applicants, the research question should be narrow enough to supervise and complete. Very broad topics such as climate change, poverty or artificial intelligence are not research proposals by themselves. The applicant needs a specific problem, context, gap, method and expected contribution.