Pokémon XD: Gale of Darkness/Cheats

Sure Spare 1 HP Attack
All you need is a Pokémon with the False Swipe attack. The Zangoose that you snag from Zook has learned it. A Pokémon with this move can almost always leave any opposing Pokémon of lower level with 1 hit point, making it an easy target for pokeballs.

Recapture Missed Shadow Pokémon
If you didn't manage to snag a specific Shadow Pokémon that you wanted, then keep fighting Mirror B. until you capture it. Mirror B. most commonly appears in Coloseum fights.

Pokémon Heal
To heal a Pokémon without a Healing Machine or a Pokémon Center, just deposit them into the P.C., and when you take them back out, they will have full HP.

Item Choices
In the interview with Acri in Gateon Port, you can get four different items, depending on how you answer the three questions she asks you. The White Herb, Mental Herb, and Quick Claw can all be purchased at Mount Battle, making the Amulet Coin the best choice to be grabbed here.

Amulet Coin: Say "Yes" to every question. Mental Herb: Say "Yes to 1 question. Quick Claw: Say "No" to every question. White Herb: Say "Yes" to 2 questions.

Shadow Dragonite
First, snag all 82 Shadow Pokémon. Then the Miror. B radar will malfunction. Head to Gateon Port and Miror B. will be at the highest point of the lighthouse. Battle him and defeat all his. Then, he will send out his Shadow Dragonite.