How To Battle Pokemon Trainer Blue

Blue is the grandson of Professor Oak, and he was the main antagonist in the First Generation Pokemon Games and Manga Series. Unlike other special characters like Green and Red, you will actually run into the Pokemon Trainer known as Blue a number of times during the Main Storyline. He will assist you along your journey, primarily with defeating Team Rocket, and he will even battle you at certain times.


You will first meet Blue in Pewter City after defeating the Pewter City Gym. Blue will introduce himself, mentioning how he is the grandson of Professor Oak and how he heard two people (your trainer and your Rival) have started their quest to catch every Pokemon in the Kanto Region. He will give you five Great Balls when he leaves. Following this, you will next see Blue when entering the S.S. Anne in the Vermilion City Harbor. He will warn you about Team Rocket as he departs the ship, even giving you the Shalour Sable as a present.
From there, you won't see Blue until you have defeated Team Rocket in both Celadon City and the Power Tower and have arrived to the Silph Co Building in Saffron City. He will come up with a plan on how to stop Team Rocket once and for all, with your trainer needing to stop them at Silph Co while he defeats any other Team Rocket Member found scattered throughout the region. Before leaving, however, he challenges you to a battle, just to make sure you're up for the task. He will only have a Level 38 Exeggutor and Level 40 Charizard in this encounter.


Later on, after having earned seven Kanto Gym Badges, you will need to proceed to the final Pokemon Gym in Viridian City. Unfortunately, it is locked when you arrived. Because of this, your Rival will suggest talking to Professor Oak back in Pallet Town. When you arrive to Oak's Lab, you will again see Blue. He will give you the Key Stone, which will allow you to Mega Evolve certain Kanto Pokemon should you have their corresponding Mega Stone in your inventory, as well as Venasaurite, Charizardite X, Charizardite Y, and Blastoisinite. After doing this, Blue will go investigate as to why the Viridian City Gym is locked. (This will actually unlock the Gym for you.)


After defeating the Viridian City Gym, Blue will again show up. He will be shocked by how Giovanni was the Viridian City Gym Leader and how the Gym was basically another secret hideout for Team Rocket. He will then mention how he thinks he should take over the Gym since Giovanni is now gone for good, noting how he has been asked to be a Gym Leader before on certain occasions. From there, we will suggest your trainer now take on the Pokemon League.


After defeating the Elite Four and becoming the newest Champion of the Kanto Region, you will be able to challenge all the Gym Leaders in a rematch on a daily basis. Because Blue has taken over the duties of the Viridian City Gym, you can battle him as well each and every day. His Pokemon will all be at Level 66 (outside of his Kanto Starter Pokemon who will be at Level 68), and it consists of Tauros, Gyarados, Aerodactyl, Alakazam, Exeggutor and Charizard (who can now Mega Evolve into its Mega Y Form).