**Super Mario Galaxy 2**, the sequel to the critically acclaimed Wii title, expands on its predecessor with inventive gravity-based gameplay and creative level design. Here are some advanced techniques and hidden secrets to enhance your experience:

1. **Spin Jump Mastery**: The Spin Jump (activated by shaking the Wii Remote) is crucial for precision landings. Use it mid-air to extend your jump distance or to stomp enemies like Goombas without taking damage.

2. **Hidden Stars**:
– **The Chimp’s Skateboard Challenge**: In *Sky Station Galaxy*, return after completing the level to find a hidden Cosmic Spirit. Complete its skateboard mini-game within 60 seconds to earn a hidden Star.
– **Green Star 1 in Yoshi Star Galaxy**: Use Yoshi’s tongue to grab a hidden Bulb Berry near the starting area, revealing a hidden path with a Green Star.

3. **Speedrun Tricks**: In *Flip-Out Galaxy*, skip large sections by wall-jumping off the rotating platforms early. This shaves off valuable time for speedrunners.

4. **Luigi’s Purple Coins**: After unlocking Luigi, revisit *Boo Moon Galaxy* to find a hidden Purple Coin challenge. Collect all 100 coins in one life for a bonus Star.

5. **Cosmic Guide**: If you fail a level multiple times, the game offers Rosalina’s Cosmic Guide, which completes the level for you. However, this disqualifies the level from 100% completion records.

For collectors, **all 242 Stars** (including Green Stars) are required to unlock the final level, *Grandmaster Galaxy’s The Perfect Run*, a brutal challenge for even seasoned players.