Bonus characters - Successfully complete "Knight's Passage" to unlock Gawain, Lancelot, and Percival in Adventure mode.

Successfully complete the indicated tasks to unlock the corresponding character in multiplayer Battle mode:

Amy Rose: Defeat the final Boss.
Big the Cat: Find Big in every level.
Blaze: Defeat Lady Percival.
Jet: Earn a "5 Star" rank on "Great Megalith" by getting a good time.
King Arthur: Collect all five of "King Arthur's Legends".
Knuckles: Defeat Sir Gawain.
Merlina: Defeat the Dark Queen in under one minute.
Shadow: Defeat Sir Lancelot.
Silver: Successfully complete the "Lancelot Returns" mission in the Deep Woods.
Tails: Successfully complete the first "Castle Camelot" mission.

Gallery profiles - Successfully complete the indicated task to unlock the corresponding profile at the "Gallery" menu:

Arthur's Legend 1: Get Arthur's Legend 1.
Arthur's Legend 2: Get Arthur's Legend 2.
Arthur's Legend 3: Get Arthur's Legend 3.
Arthur's Legend 4: Get Arthur's Legend 4.
Blacksmith (Tails): Use the Blacksmith twenty times.
Caliburn: Successfully complete "Titanic Plains - Legacy" with a "5 Star" rank.
Merlina: Successfully complete "Crystal Cave - Legacy" with a "5 Star" rank.
Nimue (Amy): Successfully complete "Crystal Cave - Rampage" with a "5 Star" rank.
Sir Galahad (Silver): Successfully complete "Knight's Passage - Legacy" with a "5 Star" rank.
Sir Gawain (Knuckles' Profile: Successfully complete "Titanic Plains - Defeat the Boss - Sir Gawain" with a "5 Star" rank.
Sir Lamorak (Jet): Successfully complete "Dragon's Lair - Legacy" with a "5 Star" rank.
Sir Lancelot (Shadow): Successfully complete "Deep Woods - Defeat the Boss - Sir Lancelot" with a "5 Star" rank.
Sir Percival (Blaze): Successfully complete "Molten Mine - Defeat the Boss - Sir Percival" with a "5 Star" rank.

Flags - Successfully complete the indicated task to unlock the corresponding flag:

Blazing Knight: Play Percival ten times in Adventure mode.
Knight Of The Sun: Play Gawain ten times in Adventure mode.
Master Cavalier: Max out on the Cavalier Style level.
Master Knight: Max out on the Knight Style level.
Master Paladin: Max out on the Paladin Style level.
Strongest Knight: Play Lancelot ten times in Adventure mode.
The True King: Successfully complete Adventure mode.

Medals - Successfully complete the indicated task to unlock the corresponding medal:

Medal of Lancelot: Defeat Lancelot, and collect the game piece after the level. This medal changes the music to "All Hail Shadow" by Crush 40.
Medal of Gawain: Defeat Gawain, and collect the game piece after the level. This medal changes the music to Knuckles' theme from Sonic Adventure.
Medal of Percival: Defeat Percival, and get the game piece after the level. This medal changes the music to that which plays when you fight Blaze in Sonic Rush.
Medal of Sonic: Successfully complete the "Knights Passage" Legacy level, and get the game piece after the level. This medal changes the music to "What I'm Made Of" from Sonic Heroes.

"Seven Rings In Hand" (Crush 40 version) song - Collect all seven World Rings in the Legacy mode levels to unlock the "Seven Rings In Hand" (Crush 40 version) song at the "Gallery" menu.

Defeating Blaze (Sir Percival) - Wait until Blaze finishes attacking, then strike twice and guard again. When she does the fire tornado, wait until she stops spinning to guard. Repeat this until Blaze has been defeated.

Defeating the Dark Queen - When the fight begins, press A or Z to dodge the first three attacks. When she pulls her hand (left or right) to attack, wait until you see the Wii-mote appear on screen to attack. Dodge what she fires at you, and attack her like before. Then, press B to use Soul Surge. Keep swinging the Wii-mote. Repeat this until she has been defeated. When she turns black, she is almost dead. Be careful; she may try to stab you. Defeat her in less than 2:30 minutes to get a lot of followers.

When the fight begins, keep slashing instead of dodging the orbs. This will save time and deflect the orbs.

Defeating Sir Lancelot - When the fight begins, stand still until he tries to attack you. When he does you can do one of two things, either block or backflip away. Backflipping puts more distance between you and Lancelot. When he finishes attacking, Jump Dash back and attack in the air. Repeat this until he has been defeated.