In HeartGold and SoulSilver Versions, Blue is Red's rival, and the gym leader of Viridian City. You can only battle him when you obtain all of the Kanto badges, he is found on Cinnabar Island.
to battle Blue in Pokemon Heartgold you must defeat the 7th gym leader, then find him on cinnabar island. Talk to him, then he will go back to his gym for you to fight
He is the Gym leader in viridian city
Blue is the 16th gym leader that you have to battle in order to catch the legendary birds and beat the game -themewtwoguy
You have to battle the last gym leader Blue in viridian city in kanto reigion.
You have to battle blue. From there the game is technically done but you can get new starters such as Squirtle.
I don't think you can battle Gardenia in Pokemon HeartGold.
how can i battle roark
Blue is at cinnebar island. surf south of pallet town. you need 7 kanto badges to battle. when you battle blaine in seafoam islands go back to talk to blue, then travel to viridian and battle him there
No, you can't battle Maylene and/or Crasher Wake in Heartgold.
you can take on any gym leader in kanto in any order (excluding blue you have to battle him last)
In Heartgold, after you get the National Pokedex and receive a Kanto starter and a Hoenn starter, talk to Mr. Pokemon. He will give you the Blue Orb. With the Blue Orb, you must go to te embedded tower, where you will find Kyogre waiting to battle you at level 50.
Once you have talked to blue on cinnabar island, you can go back and battle blue for the 16th badge.