Ah, here's a quick explanation then. This will also be good info for everyone else who is new to the series. Speaking only about the multiplayer mode:
In MH3U there are 8 levels of quests denoted by the number of stars. These are 1 Star through 8 Star. You start at 1 and complete quests til you unlock the next level, and then do the same there. These different levels can be grouped into into three ranks of difficulty: Low (1-2 star), High (3-5 star), and G (6-8 star). There are approximately 16 different boss monster that can be fought at low rank. At 3 star quests, you enter high rank. High rank has all the monster of low rank and adds more. Additionally all monster get a health and attack boost, and become more aggressive. The same thing happens at G rank. While some monsters can be fought at each level, certain ones can only be fought at the higher ranks. While there is a quest to fight Qurupeco at low, high, and G rank, Alatreon and some others cannot be fought until high rank, and a couple that are G rank only. This is why I think it should be specified what rank certain monsters should be targeted. Otherwise, one group that may be better at the game might lose because they did the G rank quest and took longer than another group that did low rank.
Singleplayer is broken up differently. Also, the monsters are weaker in singleplayer since they are meant to be handled by only one person, and there is no G rank. It's defined as: Low rank (1-5 star) and High rank (6-9 star). This is where the other problem comes in for the singles division. Someone can take down singleplayer Quru by themselves in a couple minutes, but multiplayer Quru at the same rank would take much longer.
I just want to make sure everyone's on the same page and that it's fair. If you need any more explanation let me know. I'm happy to help.
Edited by Lightning_Ninja, 12 March 2013 - 02:33 PM.