Simba

After learning the red trinity ability, use it to enter the secret waterway at the back of the Alleyway in Traverse Town. Than speak to Leon a few times until he gives you the Earthstrine Gem. Afterwards, take the gem to the Magician's study and show it to the fairy Godmother and she'll release the Spirit of Simba.

To use Simba, hold down the X Button to start charging. In the corner where you see the picture of Simba you will start to see a blue meter charge, the further it goes, the more damage it will do to the enemies around you. When you think you have charged enough let go of the X Button and Simba will use his Roar. But you have to be careful because if you get hit by a Heartless while you are charging you will lose it and have to start again.

Genie

After you lock the Agrabah keyhole, Aladdin uses his third wish to free Genie from the Magic Lamp, and than Genie becomes your summon. It takes 2 Mp to summon Genie into battle.

Genie’s attack is called Showtime. Lock on to one enemy and you should see little pictures of the Genie on the enemies. So if there is a group of Heartless, he will lock-on to more than one. Then use Showtime and he will cast a rain of spells onto the enemies around. Spells like Stop and Gravity are used.

Bambi

To get Bambi, you must get the Naturespark by completing Pooh's Honey Tree Page in 100 Acre Wood.

With you summon Bambi, she will begin to jump around and items will begin flying everywhere. However, this is how it works. There are two bars when you summon her, a yellow one and a blue lone. Everytime you defeat a heartless, the blue bar will fill up a little bit and eventually, all the way. Once this happens, you will get an item. The items get better and better as you defeat more heartless while Bambi is summonded.

Dumbo

There is a treasure chest in the belly of Monstro that contains the Watergleam. After finding it, return to Traverse Town and show the germ to the Fairy Godmother to gain the ability to use Dumbo.

When you summon Dumbo you will shrink so you can ride on his back. Then you gain control of Dumbo. Fly around and lock-on to Heartless and attack them with your water blast. While using Dumbo, you are both invulnerable to enemy attacks.

Tinker Bell

To get Tinker Bell, lock the Neverland keyhole and Tinker Bell will join your party. It takes 3 MP to summon her.

Tinker Bell will fly around you party and heal you every so often. This is great for any hard battles you face. She will also prevent Sora from being knocked out, but only once, after that, she will leave the battle.

Mushu

Mushu, who was a Guardian Spirit for an ancient clan, was banished for incessant tomfoolery. To get Mushu as a summon, you must defeat the Dragon at Hollow bastion to receive the Fireglow. After you do that, return to Traverse Town and go see the Fairy Godmother about this gem. It takes 3 MP to summon Mushu.

When Mushu is summoned he will sit on your head and wait for commands. When you lock-on to an enemy you can pick Fire Breath from the menu and he will shoot multiple fireballs at the enemy. Tip: Hold down the X-button for a constant attack.