"Kingdom Hearts 2" Quizzy Poo (PS2)

Answer: True

Sora, Donald, and Goofy fight only in rounds 1-10 and 21-30.
Sora and his summons are only used in rounds 11-20.
Sora and no special abilities are only used in rounds 41-50.

Answer: More than 20

There are 21 - simply count them up in Jiminy's Journal. They are Donald (Fantasia and Flare Force), Goofy (Twister Fusion and Teamwork), Beast (Howling Moon), Auron (Overdrive), Mulan (Dragonblaze), Aladdin (Trick Fantasy), Jack Skellington (Applause,Applause), Jack Sparrow (Treasure Isle), Simba (King's Pride), Tron (Complete Compilement), Riku (Eternal Session), Sora (Trinity Limit), Peter Pan (Never Land), Chicken Little (FPS Mode), Stitch (Ohana!), and Genie (Valor/Sonic Rave and Wisdom/Strike Raid and Master/Final Arcana and Final/Infinity).

Answer: Twilight Town

Twilight Town holds a whopping 39 chests!
Radiant Garden holds 22 chests.
Agrabah holds 26 chests.
Pride Lands holds 25 chests.

Answer: All of these exist

Along with Pain, Panic is a bad guy - and a minion of Hades'. He is one of the registration guys for the Underworld's Coliseum.
Pete is a bad guy, and he's all over the place... his only mission appointed by Maleficent is to stop Sora, although he gloriously fails on several occasions.
Mushu is Mulan's dragon. He helps out with one of Sora's combos. (Land of Dragons) Coincidentally, Mushu is a summon that Sora can use in "Kingdom Hearts".

Answer: Abu

Abu is rarely even seen (in Agrabah) - but it is actually Aladdin and Genie who are Sora's allies from that world. Genie is in fact a summon that can be used at any old time, but Aladdin is an ally only while Sora is in Agrabah.

Mulan is an ally of Sora's in the Land of Dragons. Along with Mushu, she offers him the combo Dragonblaze.
Jack Sparrow is Sora's ally in Port Royal. Sora and company must help him fight off Barbossa - a formidable boss due to his invincibility when he's out of the moonlight.
Simba is Sora's ally in Pride Lands. Sora had to help him fight off Scar on the top of Pride Rock.

Answer: Precious Amulet

Precious Amulet is completely made up. Although synthesis creation can typically make "amulets" and "charms", there is no combination of a Precious Amulet that exists in either "Kingdom Hearts" or "Kingdom Hearts 2".

Buster Band is the upgraded version of Power Band.
Orichalcum Ring is the upgraded version of Mythril Ring.
Star Charm is the upgraded version of Moon Amulet.

Answer: Power Boost

If you've obtained all energy materials, you automatically get a Power Boost from the Moogle. This can also be verified under Lists; you look next to "Obtain all energy Materials" and (assuming you've collected them all) the answer will be adjacent.

Answer: Underworld Entrance (along with the other trophies)

Sora does indeed keep the trophy with him in Items under Stock, but he does not display it. It is displayed in the Underworld Entrance between all other trophies.

Answer: True

Under Customize, cursor over Thundaga and read the description. The magic number is 15. You can test this too; 100 divided by 15 is 6.66 (repeating, of course) which means you can't cast Thundaga more than 6 times per Magic Meter (assuming it is full). You can do 10 Firaga's, 8 Blizzaga's, and only 3 Magnega's.

Answer: Sora

Donald can hold only 3.
Goofy can hold 5.
Sora can hold 6. This eliminates Sora, Donald, and Goofy holding the same amount.