Rank A is means to be killed by a group of 4 player, a play well stuff with a chocobo companion can do it, will be long but it can be done.

just a reminder:
- Rank B solo monster
- Rank A group monster.
- Rank S raid monster.

why the hp don't scale more? because since tons of people will show up, you will end with a monster with 15 billion of hp... far more dangerous than any big boss of raid or anything else they can create. the trouble with the hunt is not the hp of the monster but the fact that you have 1 monster for hundred of people. that where the system fail and why a lot of people (me included) say the system is a failure and needed to be redone for avoid this sort of stupid and unadapted system.