Alright, most of this information has been brought from my memory of the game, which i haven't played for more than 2 months, so if i mis-spell something, deal with it, and if i get some stats wrong, deal with that too. Other than that this information is really good so USE IT WELL!!!

Alright, on the floor with the orb *it's one past the thieve's hideout* you may encounter 2 Blue Funny Thieves almost directly in front of you. Right when the battle begins a few Funny Thieves will fall directly on you. My suggestion is have Dias equiped with the Funny Slayer *will kill all Funny Thieves with one hit* and run to the other side of the screen and use the item Extension Card. After you have used the Extension Card, frantically use Dias' Air Slash attack. It should be a burst of energy that goes across the screen. After a while the thieves will die out and you would have won.

Easier Way To Gain More Experience
The spot before you fight the Underground Dragon, you may run into a giant, metal robot. There is a boss that looks similar to this enemy before hand a couple of times. When you get into this battle use an extension card right away, and if you want a fol up card. With the extension card you will get 480,000 exp points. With the fol up card you will gain over 100,000 fol, not a bad deal for one easy enemy. The people i used were Dias, Claud, Opera, and Precis *Precis can be changed*. Dias' attack should be air slash, Claud's attack should be mirror slice, and Opera's attack should be Fol. Have Dias stay back and use Air Slash while the other 3 go all out.

Santa
In Theive's Hideout a guy will appear randomly, weaving through the stone thieves. Talk to this guy and he has EXCELLENT ITEMS!!! Buy a Tri-Emblem or 7 if possible because they are awesome. You may want to use Identify All to get a discount.

Switch Thief
In the Thieve's Hideout the thief in the lower right hand corner has a switch behind him. Switch the switch and continue. You will fight a Funny Thief and get a Funny Slayer *kills funny people with one blow*.

Dragon...Underground?
Yes, there is a dragon that is floating towards the end of the hidden dungeon. When you defeat this dragon you will get the "float" ability. This ability allows you to knock enemies in the air, leaving them temporarily defenseless. The easiest way i found to beat him is to use Dias' "Air Slash" with the "Holy Sword Farewell Sword" because it will hit the dragon more than once if you are far away. If you are too close, "Air Slash" will be a physical attack instead of an energy attack.

Star Over!!!?
Yeah, after you finish this horrible dungeon with monsters 2 to 3 times stronger than you, you have to start over. Not only do you have to start over, but you have to use your main character and only one more person. USE DIAS AT A HIGH LEVEL!!! Don't even attempt this until your level is at least at 150. And before you do that, you should stock up on "Go Home Frogs" which can be purchased from Santa in Thieve's Hideout.

Final Boss
Alright, you went through this whole thing and you think you are an immortal now, right? WRONG!!! Get ready for one of the hardest battles in the game. This boss is tough so make sure you have 20 fresh syrupsand 20 ressurection mists. Also have 20 blueberries, blackberries, and ressurection bottles just in case. *note: you can use the familiar ability to stock up on blueberries, blackberries, and ressurection bottles* And now for the strategies...

Claude Strategy
Bring along Opera. Use Claude with mirror slice and Opera with Fol. Have either one, preferably Opera, cure whenever they need it. Make sure you have Bunny Shoes on each.

Rena Strategy
Bring along Dias. Use Dias' "Air Slash" attack. Have Reena get the Angel's attention and cure. The Angel should go after Reena, which leaves you the chance to unload a whole lot of "Air Slashes". As soon as Rena dies, use a Ressurrection Mist as soon as possible. She will be revived and will get the Angel's attention hopefully. If Dias' life ever gets low, use a fresh syrup. This battle will be hard still, but it should be easier this way.
At the end of this battle, you should walk to the treasure chest, get the Angel Armband, and use a "Go-Home Frog". The Angel Armband raises EVERYTHING A LOT!!!

Sweep The Dungeon Clean
After you have beat the boss, you can go through the whole thing with all of your people. Collect all the items you hav emissed. Also use this oppurtunity to get your levels up if you want.