In Mobile Software Ecosystems (MSECO), keystone organizations provide mobile platforms and perform training sessions to educate and motivate developers to achieve goals, such as increasing the number of mobile apps as well as reusing and integrating information. Dedicated official staff known as evangelists performs official training sessions. However, there is little discussion about the factors that affect training sessions in MSECO. It can support evangelist in planning and performing effective training sessions. In this paper, we share results from two experimental studies to evaluate factors that may affect training sessions: (1) Case study: we identified seven impact factors in the context of a real MSECO; and (2) Survey: these factors were evaluated by 25 evangelists with respect to impact level. Those seven factors ordered by impact level are: Commitment of the partner institution; Infrastructure; Evangelist's approach; Focus on goals; Synergy; Subjectivity of the training planning; and Risk mitigation.