How can i beat Lance on pokemon soul silver?

You have a good pokemon team. If you want to beat lance, you have to make your strategy based on type advantage because dragon type pokemon have high health and defense so it might be good to double the power of your attacks. Flaffy is good for his water type pokemon while gyarados is good for the dragon pokemon since it knows blizzard and dragon rage. I personally beat him by type advantage. It is a good strategy for his pokemon! I hope that helped and good luck with your battle ;)