You should be able to get them all in your pokedex straight after you defeat the champion. If you are missing a couple, make sure you've battled everyone along the way and make sure you have visited the three lake pokemon, at lake valor, acuity and verity.

Very near the end. From the pokemon league, go over the bridge, down the rock climb rocks and then head towards the left without going down the ledge. After a few steps, it should be there. It is also available on route 224; I have two.

Head to Pastoria City (south of Veilstone) and defeat Wake. He is strong in the water type so zap him with electric and you should finish him no problem.

You have gone into the cave in the middle of that snowy valley. There are plenty of useful items there but where the grunt is covering leads you back to celestic. Get out of that cave and use rock climb towards the north. Then follow the steps and path towards the left of the screen. … Read more