Dimitri has an advantage on waterfalls and tides - So a dungeon full of water everywhere and water enemies
Moosh has an advantage of holes so a dungeon full of holes and enemies which can be killed easily with moosh slam
Ricky has an advantage on slopes and has power attack so a dungeon on those advantages
Or all animals in one dungeon thinking of which one to use
Hmm, I actually like that.
Unfortunately im all talk and could only think of ideas

oh and when i went soul tower i got the idea from this thread but a really good one lol
http://zeldahacking.ulmb.com/index.php?topic=223.0This tower could contain 8 floors instead of nine with a lot of bosses and and 2 fairy rooms to get the lvl 3 sword or biggoron sword it could bbe an optional dungeon