1. Use a Pokemon with a type advantage. Alder's team consists of Pokemon of various types, but he has a weakness to Fighting and Ground-type moves. Some good Pokemon to use against him include Lucario, Conkeldurr, Excadrill, and Krookodile.
2. Be prepared for his Dragonite. Alder's Dragonite is a powerful opponent, and it can be difficult to take down. It's important to have a Pokemon that can resist Dragon-type moves, such as a Steel or Fairy-type Pokemon.
3. Watch out for his Volcarona. Volcarona is another powerful Pokemon on Alder's team. It has a Fire/Bug typing, which gives it a resistance to many common types of attacks. Be sure to use a Pokemon that can hit Volcarona hard and fast, such as a Rock or Water-type Pokemon.
4. Don't forget about his Bouffalant. Bouffalant is a powerful Normal-type Pokemon that can be a threat if you're not careful. It's important to have a Pokemon that can take down Bouffalant quickly, such as a Fighting or Ground-type Pokemon.
5. Be prepared for a long battle. Alder is a tough opponent, and the battle against him can be long and challenging. Be sure to have a lot of healing items on hand, and be prepared to switch out your Pokemon often.
Here is an example of a team that you can use to defeat Alder:
* Lucario (Fighting/Steel-type)
* Conkeldurr (Fighting-type)
* Excadrill (Ground/Steel-type)
* Krookodile (Ground/Dark-type)
* Bronzong (Steel/Psychic-type)
* Jellicent (Water/Ghost-type)
With a well-prepared team and a good strategy, you'll be able to defeat Alder and become the Champion of Unova!