Why can't i travel further on pokemon diamond

Question

i am currently at the battle tower. the two other routes are blocked, the people blocking the routes mention the battle tower and I've already battled and won there in each of the rooms, so why can't i go further?

Answer 1

You have to get the national dex.. To get the national dex you have see every pokemon in the sinnoh dex.. After seeing every sinnoh pokemon, go to prof. rowan and he will give you the national dex..

Answer 2

u need national dex

Answer 3

you must have a national dex because the pokemon you encounter at the blocked routes are pokemon like fearow, ratata, bannete. To get the national dex you have to see every kind of pokemon that are in sinnoh. then go to rowan and he'll congratulate you . then oak will come in and upgrrade your dex to national mode and you also get a pokeradar. if you have pokemon like lummineon left, then there is a female trainer with one on the sea of sunyshore.she is the first trainer you will encounter.

hope i helped