Phasing out coal-fired electricity is an urgent global task, critical to efforts to mitigate climate change and air pollution. Despite the growth and increasing competitiveness of renewable energy, phase-out progress is slow, with coal-fired power even reaching an all-time global high in 2021. A key factor blocking or delaying this energy transition is the active resistance of coal regime actors with vested interests. However, there is still a lack of a systemic understanding of why some actors are more influential in shaping transition processes such as changes in policies or institutions. In this article, we present a comparative case study of the political struggle around the coal policy in Germany and Japan. We use the Endowment-Practice-Institutions (EPI) framework to analyse how actors try to destabilise or maintain the institutional arrangements underpinning the coal regimes in these countries and why some are more influential in shaping the policy outcomes. Our findings show that while actors' strategies are largely determined by the socio-political context they are embedded in, there are also certain patterns and common sequences of practices. These include commissioning a study, disseminating it through various networks and social media channels, mobilising the public through demonstrations, and engaging in advocacy with the aim of increasing the political bargaining power. Our analytical framework, which can be applied to various settings, helps to understand why certain policy outcomes occur amidst efforts to spur or stall energy transitions, and why regimes are destabilised in some case - but not in others.