Yes
just battle and capture as many different types of wild Pokemon as you can, for me i had to battle a certain trainer because my pokedex was missing one so search on the enternet to find a certain Pokemon you might be missing
go to the vally windworks trade for it or battle someone who has it
If you see a Pokemon in the battle frontier you have not yet seen, it will not record it. The only way you can add that Pokemon to your pokedex is if you see it outside of battle frontier.
Wild Pokemon in Battle Frontier like Sudo Woodo and Smeargel will be registered to your Pokedex, but the Pokemon owned by trainers you battle wont...
you get the sinnoh pokedex from professor Rowan afteyou battle the starly with one of the Pokemon in the bag and say yes to the professor and you get the Pokemon and the pokedex.
You have to battle them.
you have to find all of the Pokemon in your first pokedex note you don't have to catch them all but you have to see them and the battle park doesn't record in your pokedex
even though i am a master at the game, i don't know. probably when you get the national pokedex.
Just go to Pokemon platinum central and click on pokedex and it shows you where to battle all the Pokemon in sinnoh.
The Pokemon you see do not go in your pokedex.
No.
You can't Complete the Pokemon Battle Frontier its just for fun. You have to complete the shinnon Pokedex to go on to Natoinal Pokedex.