you have to trade them from a game that has the national dex.
First you need to have beat the Elite Four and gotten a National Pokedex. Then you have to keep saying yes to being envious of him and then he'll tell you the Pokemon he saw that day. The Pokemon he sees changes each day.
In the pokedex its considered rare due to its many Chinese mysteries. But in reality its just a regular Pokemon. Another rare Pokemon from the pokedex is Arcanine.
7. you can get even more using any Pokemon which has the pickup ability(i prefer meowth or mewtwo). the higher the level of your Pokemon, the more the chances of getting rare candies.
use pokeradar in 9x9 grass to catch rare pokemon or talk to dawns sister and she will tell you where to see the rare pokemon (you need the national dex) and you can also find some rare pokemon in the trophy garden (no need pokeradar) just talk to Backlot and he will tell you what pokemon are in the garden (the pokemons there are not so very rare exept castform and meowth)
You can Find ditto with apoke radar in route 218.It is very rare so be cautious.You need a national pokedex for this.If you do find the grass that is shaking wildly there you might find ditto.You need a lot of ultra balls for this!
you just have to keep looking but without cheats there is only about 1 shiny Pokemon per game and it is really rare
You dig for it under ground after you get the national pokedex and the are rare.
Basically, the only things you can do are catch rare Pokemon and attempt to complete your national pokedex.
You find them in the trophey garden after getting the national pokedex. Be warned: they are extremly rare.
You get a pikachu by going to Mr. Backlot's yard and looking in there. To get other rare Pokemon from other reigons you have to get the National PokeDex.
You talk to Dawn's sister after you get the national pokedex and she will tell you where to catch certain rare pokemon. Sometimes you will get a Phanphy.
After you obtain the National Pokedex, talk to the owner of the mansion that likes to brag about rare Pokemon in his garden. It will be a different Pokemon every day.
After Obtaining National Pokedex, Beautifly can be found at Eterna Forest, Route 224 and Route 230 they are RARE
Moltres, Articuno, Zapdos, Raikou/Suicune/Entei (depends on what starter Pokemon you chose), Mewtwo and Unown (in the pokedex its considered rare).
Munchlax is found via honey trees but I have never caught him, he's rare. Type in 'pokemon pokedex' on Google.
Once you complete the National Pokedex Professor Oak - or Professor Rowan in DP and Platinum will have unlimited Rare Candies for you. IN ORDER TO GET THIS YOU HAVE TO COMPLETE YOUR NATIONAL POKEDEX.
Some rare Pokemon are Mesprit, Azelf and Uxie but there are many moreWell, some rare Pokemon I've observed and caught are Giratina, Heatran, and Dialga. There is one Pokemon that I've only seen and had not yet caught, which was Regigas in the tower in Snowpoint City. It is annoying that you have to buy another Pokemon game to complete the National Pokedex. Like that you can't catch Regigas without Regice, Regirock, and Registeel, because those Pokemon aren't available in Pokemon Diamond, which is completely unfair!