The Mushrooms eh?
Well, maybe their size do have a significant... Or a relation to the ORG member w/ the same number...
But I've just thought of something, what if its just something Nomura and the crew did so that they'll be able to tell which mushroom is which? XD
Anywho... I think the reason Axel runs away from the organization is because he can't possibly face the ORG by himself... He can probably handle one member but not all of them at the same time...?
I don't think they'd ALL take him on at once! O______O He DID run from Saix. >.> He seems afraid of him. Ironically, with Mushroom no.8 you have to keep it off the ground and before you start the mini game, it's hiding neck down in the ground. >_> Also, each Organization Mushroom dose have a characteristic of an Organization member.
I = Dodge commands, like the ones used in the last battle with Xemnas
II: Dodge projectiles like with Xigbar
III. Flies around and.... drops stuff... well, Xaldin flies around, so let's keep it at that. >_>
IV: Defeat Mushroom clones and don't let them touch you, like the Clones Vexen makes in the remixed battle
V: Attack the sleeping and regenerating Mushroom, sort of like Lexaeus's points constantly going up, also the Heartless IS huge like Lexaeus.
VI: continuously appearing Organization members... I guess it has to do with illusion like Zexion uses.
VII: Defeat the Berserk Mushroom! SAIX GOES BERSERK! RAAAWR! >.<
VIII: Keep on hitting the Mushroom in the air and don't let him touch the ground, like how in the Axel battle yu have to knock him in the air to get rid of the fiery floor.
IX Keep hitting him so he can spin and dance! Like how Demyx likes to sing and dance.
X: Play a gambling game to find the real mushroom, then attack it.
XI: Hit it 99 Times and bring the number down to 9, like how Marluxia has that number above your head that matches your level.
XII: Defeat 40 copies in 30 seconds and we all know that Larxene copies herself in KHII:FM. >.<
So, they pretty much ARE meant to represent Organization members. Their the cutter version of the Organization.... without a Roxas.