Fungal diseases pose a significant threat to global agriculture, leading to major crop losses and harmful mycotoxin contamination. Effective management of these diseases is crucial for safeguarding crop production and ensuring food safety. With a growing emphasis on sustainability, there is increased interest in using biological control agents (BCAs) and biostimulants with protective effects (BPEs). This paper provides a comprehensive set of methods or protocols for rapidly screening the protective potential of BCAs and BPEs, covering assessments from pathogen-only evaluations to those involving both the pathogen and the host at early stages. By promoting standardised and reproducible methods, this review offers a concise guide for initial evaluations, helping to identify promising microorganisms and substances for further research. These methods allow for comparisons between BCAs/BPEs and conventional chemical treatments, the assessment of potential synergies, the ability to control fungicide-resistant strains and the evaluation of phytotoxicity. The goal is to improve the understanding and integration of BCAs and BPEs into agricultural practices, reducing reliance on agrochemicals and promoting sustainable management of fungal diseases. Future research should expand the range of biostimulants under investigation and refine evaluation methods to maximise their effectiveness in real-world applications.