Onslaught [Wii]

Expert difficulty
Successfully complete the game under the Hard difficulty setting.

Ultra difficulty
Successfully complete the game under the Expert difficulty setting.

Weapon upgrades
Complete the indicated task to obtain the corresponding weapon upgrade. Each weapon has two upgrades that are treated as additional weapons. They can also be used with a new game on the same saved game file.
Assault Rifle level 2: Obtained from box in mission 5.
Assault Rifle level 3: Complete the game under the Ultra difficulty.
Grenades level 2: Complete missions 1, 2 and 3 under the Normal difficulty with an "S" rank.
Grenades level 3: Complete missions 1 to 8 under the Hard difficulty with an "S" rank.
Rocket Launcher level 2: Complete missions 9, 10 and 11 under the Normal difficulty with an "S" rank.
Rocket Launcher level 3: Complete missions 1 to 12 under the Ultra difficulty with an "S" rank.
Shotgun level 2: Obtained from box in mission 11.
Shotgun level 3: Complete the game under Expert difficulty.
SMG level 2: Obtained from box in mission 3.
SMG level 3: Complete the game under Hard difficulty.
Whip level 2: Complete missions 5, 6 and 7 under the Normal difficulty with an "S" rank.
Whip level 3: Complete missions from 1 to 8 under Expert difficulty with an "S" rank.

Less enemies
Destroy the hives as soon as possible, as enemies will continuously spawn from them.

Mission 2
Keep some distance away from the hives. Enemies will spawn faster the nearer you are to them.

Mission 5
Let the enemies come to you. After destroying a wave, go around and take out the enemies blocking the radar. You can also use the tank like a turret if needed.

Destroying multiple enemies
* You can set a tank to self destruct by pressing A. When it explodes it may take out a group of enemies.
* Hold B when firing the rocket launcher. You can now target several enemies and fire multiple rockets.
* Use the Laser Whip to save ammunition. It recharges and will not run out of ammunition. You can use it to take out up to three enemies at a time.
* Although the shotgun is less useful at a distance, you can take out a group of enemies by rushing them and firing a few shots.