I'm assuming you mean how you can release your Pokemon so they can walk alongside you, right? Well, the only way you can do that is in Amity Square located in the northwest or northeast corners of Hearthome City in the Diamond, Pearl, and Platinum games. You cannot send them out to walk with you anywhere outside of Amity Square.
It depends what level and how many gym badges you have 1 badge-level 0-20 2 badge-level 20-30 3 badge level 30-40 5 upto 50 to 60 7 60 to 70 8 any level
its for decoration
Nothing
hearthome city
in canalave city under the Pokemon center
You go to Sunyshore city. There will be a PokeBall Somewhere, You open it and there is a thunder stone. That evolves ur Eevee u can get from bebe (harthrome city,house next to poke center) into Jolteon. x]
When in Jubilife City, take the path that goes to east and follow it through the cave and you will enter the city.
you cant but you can if you go to hearthrome city and go to the park at the very top of the city
HeartGold and SoulSilver are the only games right now where your Pokemon follow you EVERYWHERE. You can, however, have cute Pokemon follow you in amity square (HeartHome city). There, every 200 steps, talk to your Pokemon and you'll find an accessory or berry Hope i helpedd :)
If you mean they will be behind you throughout the game, then no, they won't. The only games that allowed Pokemon to follow behind for the adventure were Pokemon HeartGold and SoulSilver. In Pokemon Diamond, Pearl, and Platinum, you can go to the Amity Square, which is connected to Hearthome City, where certain chosen Pokemon can follow you for that area, however.
find the ice path and follow it
Either go to the thing in the north of Hearthome city or change the entire game for Pokemon soulsilver or heartgold
you use whirpool when you are able to when next to a whirpool between cianwood city and olivine city you will encounter lugia.
follow him still dont no where retrace your step how to get to pastoria city
Cynthia(pokemon league champion) will give it to you when you follow the team galactic grunt from Pastora City.
go to splatsport city then a guy will be being intervuid follow him and then go back to lilycove CITY
Go West from Ecruteak City. There should be a gate house. Then just follow the path, it's pretty straightforward.