Sonic Adventure DX: Director's Cut

Sonic's Boss Batle

 * Chaos 0
 * Egg Hornet
 * Chaos 4
 * Chaos 6
 * Egg Viper
 * Perfect Chaos

Tails' Boss Battles

 * Egg Hornet
 * Chaos 4
 * Egg Walker

Knuckles' Boss Battles

 * Chaos 2
 * Chaos 4
 * Chaos 6

Amy's Boss Battles

 * Zero

Gamma's Boss Battles

 * E-101 Beta
 * E-103 Delta
 * E-104 Epsilon
 * E-105 Zeta
 * E-101 Mark 2

Big's Boss Battles

 * Chaos 6

Sonic's Upgrades

 * Light Speed Shoes Allows Sonic to use 'Light Speed Dash', which lets Sonic run at light speed on a trail of rings. Chargeable. (Needed)
 * Crystal Ring Makes charge-up time of 'Light Speed Shoes' shorter by two seconds. (Recommended)
 * Ancient Light Gives Sonic the 'Light Speed Attack'. Works the same way as 'Light Speed Dash', but use near an enemy to attack multiple enemy's at the same time.

Tails' Upgrades
Jet Anklet

Where found: Station Square sewer (Fly upwards in a small, square hole). What it does: Allows Tails to fly faster.

Rhythm Badge

Where found: The Past. What it does: Allows Tails to do the 'Tail Whip Attack' repeatedly.