Mario Kart DS/Level 2

Mission 2-1
The first step is getting a well-timed power boost to effectively ram into the first crate and continue at full speed. Continue hitting the next few crates. Eventually you will reach a wooden dock with two boxes on both ends of it. Drive through the catawalk and hit the crate at the farthest end. Then, hit reverse and try to use the bottom screen as an aim aide to break the other crate on the dock. This will take some practice, so don't expect to get it the first time. Now, make a tight turn around, back inland, and continue breaking the remaining crates. Soon you will reach a barricade, where you should make a powerboosted right turn into a concrete dock to break the final crate.
 * Description: Crash into all 10 wooden crates and destroy every one!
 * Course: Delfino Square
 * Character: Wario
 * Time: 55 seconds

Mission 2-2
Getting a well-timed power boost, simply drive into all of the ten coins to collect them. Try not to powerboost, as you may not be able to easily complete powerboosts with Yoshi's standard kart and still stay well in the path of the coins.
 * Description: Collect all 10 coins!
 * Course: Figure 8 Circuit
 * Character: Yoshi
 * Time: 30 seconds

Mission 2-3
If you want to get 3 stars on this mission, you must make all *perfect* power boost turns by making lots of room for Donkey Kong to boost in to. When power boosting with this combination, you must realize the power boosts are extremely linear and not as fluid as, say, the lightweight characters' power boosts are. With a well-timed starting power boost, make a wide power boost down the initial turn and prepare another power boost as you drift through the first numbered gate. Right before entering the gate, release the power boost you've prepared and veer off to the left during your boost to avoid the edge of the bridge. Then, make two wide powerboosts through the next wide turn and drive directly into a mushroom. Once you boost through the grass and pass the second gate, prepare another power boost and release it when you pass through the third gate. From this point on, do not power boost! Drive through the next mushroom to gain momentum and begin a drift to the left. After passing the fourth gate, release your drift to catch the next mushroom and the final gate at the end of the track.
 * Description: Drive through all 5 numbered gates in order!
 * Course: Donut Plains 1
 * Character: Donkey Kong
 * Time: 45 seconds

Mission 2-4
Luigi, in this situation, has a slightly longer power boost than other characters, making his turning capability during power boosts less fluid. This means that you will have to put a little extra effort in to aiming his power boosts before you release them. Getting a well-timed start boost, prepare a power boost and release it in the direction of the first item box during a right curve in the path. Power boost again through the next left curve to redeem the second item box. Use a mushroom to boost yourself through the straightaway and into the third item box. Use another mushroom to catch the fourth item box over the ramp. Before the next right turn, use another mushroom and drift at the same time into the final item box as the item box approaches the middle of the turn.
 * Description: Destroy all 5 item boxes!
 * Course: Luigi's Mansion
 * Character: Luigi
 * Time: 30 seconds

Mission 2-5
Peach is horrible when it comes to being a power booster, so the best optimization you could make to achieving this mission with three stars is to use a fully-powered start boost. With a well-timed start boost, simply drive into all groups of coins to collect them and complete the mission.
 * Description: Collect all 20 coins!
 * Course: Cheep Cheep Beach
 * Character: Peach
 * Time: 30 seconds

Mission 2-6
It's best that you don't power boost at all in this mission, becuase you simply don't have the room Wario needs to make a power boost. Furthermore, don't get a start boost either, because you will miss the first set of Pokeys and possibly end up somewhere in the path of the second set of Pokeys. With no start boost, break and stop directly on the middle box of the first set of item boxes. By stop-drifting using +  to aim left and  +  to aim right, aim at the Pokeys within reach and press  to release the bob-omb. If done correctly, each Pokey you hit should be obliterated by the bob-omb's blast, and you should instantly get a new bob-omb from the item box respawning. Continue doing this for the next row of Pokeys and the final Pokey before the barricade. Remember not to get too close to a Pokey before blowing it up, or you'll blow up with it!
 * Description: Use bob-ombs to destroy all 5 Pokeys!
 * Course: Desert Hills
 * Character: Wario
 * Time: 55 seconds

Mission 2-7
Power boosting in this level is immensely required in order to get a 3 star ranking on this mission, and luckily for you, Toad is a well-suited power booster. With a well-timed start boost, drive through the first numbered gate and onto the zipper ahead. After flying off the zipper, you'll find the eighth numbered gate is placed almost directly in front of the zipper's release path, so begin power boosting to the left to enter the farther second numbered gate on the left. Get a mushroom and press to release it and fire yourself into the third numbered gate. Start a drift to the left and ride on to a series of zippers to pass through the fourth numbered gate. Before riding off the last zipper, position yourself into the direction of the edge of the zipper with a charged power boost and release it once the momentum of the last zipper has worn out. At the end of the turn fly off the next zipper and into the sixth numbered gate on the farther right. Use one-sided power boosts to propell yourself through the seventh and eighth numbered gates on the left. Power boost your way through the ninth numbered gate (or use a mushroom if you have one.) Once at the turn before the finish line, power boost to and drift on to the right of the zippers to enter the final numbered gate.
 * Description: Drive through all 10 numbered gates in order!
 * Course: Luigi's Circuit
 * Character: Toad
 * Time: 55 seconds

Mission 2-8
Snaking is tough with Peach, so the best you can get, as far as power boosting goes, is one-sided power boosts before each turn in Baby Park. With a well-timed start boost, drive Peach into an item box and release a star while she power boosts through each turn. While she's on a striaghtaway, do two more wide one-sided power boosts and power boost into the next turn with a new star. Repeat this process until you've completed six power boosts. Once you have, simply drive through the track to complete the remainder of the laps with a star active and a drift through each turn.
 * Description: Perform six power-slide turbo boosts in 3 laps!
 * Course: Baby Park
 * Character: Peach
 * Time: 55 seconds

Boss Stage
This boss fight requires that you do not power boost at all. With a well-timed start boost, drive through both of the Eyerok's hands and obtain a green shell. Turn around and face the Eyerok until he attempts to move one of his hands to hit you. Notice how he leaves his other hand still. While his strong hand approaches you, quicky drive forward in the direction of the Eyerok's other hand and release a green shell into his eye. He'll get up, so repeat the process once more. After the second hit, the Eyerok won't leaves his hands unguarded and instead move both of them in a juke-ish style. Approach the Eyerok and wait until one of his hands touches the ground while the other is in the air. When the time is right, release a green shell at the Eyerok's eye to finish him for good.
 * Description: Hit the Eyerok's eyeball 3 times with shells!
 * Course: Sand Arena (name based on surroundings)
 * Character: Mario
 * Time: 5 minutes