This study evaluates the effectiveness of coaching in the Ideation of Leadership Development Program (LDP) Level 3 at PT. PLN (Persero), focusing on Coach-Client Relationship theories (Diller et al., 2022) and the ADKAR model by Hiatt (2006). It investigates the influence of coach-coachee dynamics, including Working Alliance – Task and Goal, Perceived Empathy, Perceived Need Supportive Behavior, and Closeness, on the success of the coaching process. Additionally, the research assesses the ADKAR model’s components (Awareness, Desire, Knowledge, Ability, and Reinforcement) and Team Effectiveness based on Process Criteria (Effort-Related, Strategy-Related, and Knowledge & Skill-Related) in group project facilitation. Utilizing a quantitative approach, online questionnaires were distributed to 19 individuals who met the necessary criteria, including being participants in two coaching sessions of Ideation 3 Batch 5 and holding positions as potential leaders three tiers beneath the board of directors, consisting of Managers in Service Units, Vice Presidents in subsidiaries, and Assistant Vice Presidents. The responses then would be analyzed via IBM SPSS 27.0. Results indicate significant correlations between Coach-Client Relationship, ADKAR model, and Team Effectiveness, enhancing the understanding of coaching in personnel development. This finding highlights the necessity of a well-aligned coaching process to foster effective individual change readiness. Moreover, the finding also reveals that the coaching process extends beyond individual development and has a significant influence on team collaboration and effectiveness. A well-aligned coaching process can more effectively prepare individuals for the transitions and developments required in leadership roles and equip them to contribute positively to team environments. While this study contributes to a better understanding of coaching as a method for people development, there are some limitations concerning the sample and limited time of the study. Future research with a larger and varied sample, across-case data collection, and various additional data is needed. Testing with before-after questionnaires, forum group discussions, and a mixed-method approach would be particularly interesting, including diverse leadership levels and genders.