How do you get the guy blocking from getting to lugia in Pokemon HeartGold and SoulSilver?

You can't actually *get* the guy blocking Lugia to move. He's a plot device and will only move after you've done a few key things:

1. Defeat the Elite Four and become Champion: This is the primary requirement. You need to prove yourself worthy of challenging Lugia.

2. Talk to the guy: Once you've become Champion, approach the guy blocking the way to Lugia. He'll recognize your strength and let you pass.

There's no trick or shortcut to make him move sooner. It's all about progressing through the game and earning the right to face Lugia.