Typical Charge Strength M skill specialist: wants a combination of skill and speed boosts.
BFS and HB brings as much strength as 1 extra trigger per day.
Ampharos is a typical Charge Strength M user. The ideal combination would be STM+HSM+skill up nature. Anything further is a bonus. However, because this skill's only purpose is to bring "general Snorlax strength", BFS and HB are equally applicable. Run calculations on RaenonX to confirm your specific output, but in most cases, both of those subskills bring the equivalent of an extra proc per day. So, BFS+STM+skill up nature is roughly equal to STM+HSM+skill up nature.
However, one side effect of choosing BFS is varying output depending on your map's bonuses. Your Ampharos will perform best when electric is favorite berry. But on certain event weeks where skill rates are boosted 1.5x, your Ampharos will perform slightly worse comparatively due to its lesser skill output.
HB is more insulated from this effect by boosting your team by 5%, which is always proportional - just make sure the rest of your team is good.
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