Street Fighter 4 - Unlock Akuma

Unlock Gouken:
First, unlock Akuma, Sakura, Dan, Cammy, Fei Long, Gen and Rose then Fight him on arcade mode. Get at least 2 perfects and 2 Ultra Finishes to unlock him.

Unlock Cammy:
End the arcade mode with Crimson Viper

Unlock Dan:
End the arcade mode with Sakura

Unlock Fei Long:
End the arcade mode with Abel

Unlock Gen:
End the arcade mode with Chun-Li

Unlock Rose:
End the arcade mode with M.Bison

Unlock Sakura:
End the arcade mode with Ryu

Unlock Seth:
End the game with all the other characters

Achievements:

All Dolled Up
Reward: 10 Points
Objective: Set your Title and Icon.

Arcade Rat
Reward: 20 Points
Objective: Clear Arcade Mode with 1 character on Medium or higher difficulty.

Challenge Expert
Reward: 30 Points
Objective: Clear all Challenges in Challenge Mode.

Challenger
Reward: 10 Points
Objective: Clear a Challenge in Challenge Mode.

Color Guard
Reward: 10 Points
Objective: Unlock all Colors.

Crowd Pleasing Master
Reward: 10 Points
Objective: Perform 10 Personal Actions.

EX-cellent Master
Reward: 20 Points
Objective: Perform 100 EX Special Moves.

Focus Master
Reward: 10 Points
Objective: Perform 100 successful Focus Attacks.

Icon Master
Reward: 50 Points
Objective: Collect all Icons.

Last Man Standing
Reward: 20 Points
Objective: Clear HARD Survival in Challenge Mode.

Legendary Champion
Reward: 50 Points
Objective: Defeat Gouken and clear Arcade Mode in Hardest difficulty.

Medal Collector
Reward: 10 Points
Objective: Collect 100 Medals.

Medal Hunter
Reward: 10 Points
Objective: Collect 500 Medals.

Medal Master
Reward: 30 Points
Objective: Collect 1,000 Medals.

Medals Get
Reward: 30 Points
Objective: Collect all Medal types.

No Challenge Too Hard
Reward: 20 Points
Objective: Clear HARD Trial in Challenge Mode.

No Sweat
Reward: 10 Points
Objective: Unlock all Personal Actions.

Rapid Fighter
Reward: 10 Points
Objective: Clear NORMAL Time Attack in Challenge Mode.

Save Your Quarters
Reward: 30 Points
Objective: Clear Arcade Mode without using a single continue on Medium or higher difficulty.

Simply Perfect
Reward: 10 Points
Objective: Achieve 10 Perfect victories.

Special Move Master
Reward: 10 Points
Objective: Perform 100 Special Moves.

Speed King
Reward: 20 Points
Objective: Clear HARD Time Attack in Challenge Mode.

Storied Reputation
Reward: 30 Points
Objective: Clear Arcade Mode with all characters on Medium or higher difficulty.

Sunny Daze
Reward: 40 Points
Objective: Perform 365 flashy background finishes.

Super Combo Champion
Reward: 10 Points
Objective: Perform 50 Super Combo finishes.

Super Combo Master
Reward: 10 Points
Objective: Perform 100 Super Combos.

Technical Fighter
Reward: 10 Points
Objective: Clear NORMAL Trial in Challenge Mode.

The Gold Standard
Reward: 50 Points
Objective: Earn gold medals in all challenges.

The World Warrior
Reward: 20 Points
Objective: Unlock all characters.

Title Master
Reward: 50 Points
Objective: Collect all Titles.

Tough Cookie
Reward: 10 Points
Objective: Clear NORMAL Survival in Challenge Mode.

Ultra Combo Champion
Reward: 10 Points
Objective: Perform 50 Ultra Combo finishes.

Ultra Combo Master
Reward: 10 Points
Objective: Perform 100 Ultra Combos.

World Champion
Reward: 30 Points
Objective: Clear Arcade Mode on Hardest difficulty.

Multiplayer:

10 Years Too Early
Reward: 20 Points
Objective: Win 50 Xbox LIVE battles. Ranked match or player match

10 Years Too Late
Reward: 50 Points
Objective: Win 100 Xbox LIVE battles. Ranked match or player match

First Victory
Reward: 20 Points
Objective: Win 1 ranked match.

Hard Fought Battles
Reward: 20 Points
Objective: Play 200 Xbox LIVE battles. Ranked match or player match

I Got Next
Reward: 30 Points
Objective: Win 5 ranked matches in a row.

Lobbyist
Reward: 10 Points
Objective: Create 10 multiplayer lobbies.

Playing To Win
Reward: 50 Points
Objective: Win 10 ranked matches in a row.

Proof of Battle
Reward: 20 Points
Objective: Play 500 Xbox LIVE battles. Ranked match or player match

Taking On All Comers
Reward: 10 Points
Objective: Fight 10 opponents via fight requests.

The Journey Begins
Reward: 20 Points
Objective: Win 10 Xbox LIVE battles. Ranked match or player match

The Line Starts Here
Reward: 20 Points
Objective: Win 3 ranked matches in a row.

The Road to Battle
Reward: 10 Points
Objective: Play 100 Xbox LIVE battles. Ranked match or player match

Unbeatable Fist
Reward: 0 Points
Objective: Ruler of All

Way of the Fist
Reward: 10 Points
Objective: Win 5 Xbox LIVE battles. Ranked match or player match