Connection bonuses:
Connect to Castlevania Judgment to unlock the following bonuses.

Courses 1, 2, and 3
Increased level cap
Practice mode
Queen Of Hearts item
Record option
Royal Crown item
Wireless Race option 

Albus mode:
Save all the villagers and successfully complete the game.

Boss Rush mode:
Save all the villagers and successfully complete the game.

Sound mode:
Save all the villagers and successfully complete the game.

Hard difficulty:
Successfully complete the game.

Hard mode level 255:
Successfully complete Hard mode level 1. Alternately, link to Castlevania: Judgment on the Wii.

New Game+:
Successfully complete the game. Highlight your cleared saved game file then press Right to select the clear sign to start another game session in New Game+ mode.

Boss medals:
Do not get hit during a Boss fight. After winning, a treasure chest with a medal for that particular Boss will appear.

Queen Of Hearts:
Successfully complete Hard mode in any capped level to unlock the Queen Of Hearts item. It reduces half of what a union would normally cost.