:Sonic:
In Camelot Castle Get a 5-Star Rank on the Rush Hour Mission.

:Sonic Battle Mode:
In Knight's Passage Get a 5-Star Rank on the 'Defeat 10 Will-o'-Wisps' Mission.

:Lancelot(Shadow):
In Camelot Castle Get a 5-Star Rank on the 'Put out 10 Fires' Mission.

:Lancelot(Shadow) Battle Mode:
In Shrouded Forest Get a 5-Star Rank on the 'Don't Touch the Ground' Mission.

:Gawain(Knuckles):
In Titanic Plain Get a 5-Star Rank on the 'Open all Locks' Mission.

:Gawain(Knuckles) Battle Mode:
In the Great Megalith Get a 5-Star Rank on the 'Destroy 12 Columns' Mission.

:Percival(Blaze):
In Molten Mine Get a 5-Star Rank on the Ultimate Challenge Mission.

:Percival(Blaze) Battle Mode:
In The Cauldron Get a 5-Star Rank on the 'Escape the Cauldron' Mission.

:Nimue(Amy):
In Deep Woods Get a 5-Star Rank on the Ultimate Challenge Mission.

:Blacksmith(Tails):
Visit/Use the Blacksmith 50 Times.

:Merlina:
In Crystal Cave Get a 5-Star Rank on the Chain of Rings Mission.

:King Arther:
In Faraway Avalon Get a 5-Star Rank on the Total Rampage Mission.

:Knave and Knife:
In Knight's Passage Get a 5-Star Rank on the Perfect Challenge Mission.

:Knight of the Wind and Legendary Sword:
In Faraway Avalon Get 5-Star Rank on the Ultimate Challenge Mission.

Sorry but I don't know how to unlock Voice Clips for
Galahad(Silver) and Lamorak(Jet)...

Perform the actions below to unlock the desired characters:


Amy Rose - Defeat the Final Boss

Blaze - Defeat Sir Percival(yes, according to the game, she's a sir)

King Arthur - Collect all 5 of "King Arthur's Legends" story books

Knuckles the Echidna- Defeat Sir Gawain

Shadow the Hedgehog- Defeat Sir Lancelot

Miles "Tails" Prower - Finish the first Camelot Castle Mission .

Sir Lamorak(Jet the Hawk)- Get a 5 star ranking on Great Megalith, 1st mission.

Sir Galahad(Silver the Hedgehog)- Complete the mission "Lancelot returns" in the Deep Woods stage.

Unlockable: Seven Rings in Hand (Crush 40 Version)
To unlock song "Seven Rings in Hand" in the gallery, collect all seven World Rings in the Legacy stages.