How do you get to Route 224 on Pokemon Diamond?

Answer 1

You can't get there until you beat the Elite Four and obtain the National Dex. Once you do, fly to the Pokemon League and go back to the cave. Go right and the guy blocking the path will be gone, allowing you to go to route 224.

Answer 2

first you have to get the national pokedex

then go inside the end of victory road go all the way down use rock climb go left then up behind the old man go up the stairs over the bridge go up then right and down

inside the cave entrance there someone needs help you decide to go with him

get past the cave and go outside and you are at route 224

make sure you stock up on max repels bring your best guys

:) hope this helped