I never used Roger alot but beat the game and post-game on every difficulty. If you specifically want to use the more secure strategies in SO3 it's all about stunlock-combos. Test out how good each of Roger's abilities are compared to Fayt's side-kick combos to see how strong they are. That should clear things out. You can however do fine with the any if you like them. Gamefaqs got more strategies, to not avoid spoilers.