after fixing the power plant go to the radio tower in kanto and they will give you a pokegear item to sound like a poke flute :D go to the snorlax and at las go through diglets cave and that way...
after meeting entei,raikou,and suicune in the burned tower in etrueck city, entei and raikou will be running all around jonto at lv. 40 . you can check your pokegear to see where they are.
You can either just buy it in the Pokemart but you can also go to the Pharmacy in Cinnabar but they will only give you medicine if your Pokemon is really sick.