When you arrive at Ecruteak City, it's time to begin exploring. There are plenty of residential locales to see, and much more, so let's get going. Of course, you're first going to want to find and utilize the town's Pokemon Center and Poke Mart, so you can heal your Pokemon and buy needed goods, respectively. Then, you should next begin exploring the town's many residences. You'll find inhabitants in all of them, and you can speak with them about all sorts of different things. When you speak to one of the inhabitants of these houses in particular, however, you'll receive the Dowsing Machine, an item that will allow you to find well-hidden items all around you. More information on it can be found in the Side Quests section of this guide, if you're interested in browsing the entry on it over there.
Otherwise, there are four buildings, in particular, that will catch your eye here, and all four of them should be visited in sequence (if possible). First, visit the town's gym, located in the southwestern corner of the city. You'll be immediately kicked out when you enter, but you'll find out that the gym leader, Morty, has gone to a location known as the Burned Tower. Obviously, we'll have to follow up with him by going there ourselves. But before you do that, visit the theater in the middle of town. Here, you'll encounter a Team Galactic Grunt giving one of the dancers a hard time. Speak to the Grunt, and you'll be thrust into a battle with him. Fell him easily (he only has a level twelve Koffing), and as you leave, you'll be intercepted by an elderly man. He'll hand over the all-important HM03 to you, which can teach an eligible Pokemon the Surf ability. It's a necessity to get this move, so don't miss it!
Finally, you can explore the northern end of town. There's a humongous building that dominates the northern side of town, though without the badge from this town, you can't yet explore there. So for now, you can just ignore it all together. Instead, voyage to the west of the large building, and you'll find the location known as the Burned Tower. This is where Marty, the town's gym leader, ran off to. And if you want to battle him in the gym and earn his much sought-after badge, then you're going to have to find him in the tower and somehow coerce him back outside, and ultimately, back to his gym. So, let's get to it.
Your time spent in the Burned Tower will be extremely brief, indeed. There are only three "wild" Pokemon to find and fight here as you go about your business (Zubats, Rattatas and Koffings), and there's little else to see or do (though there are some trainers to fight). As you enter the tower and head rightward (you'll be unable to proceed to the left), you'll run into Morty, the gym leader here at Ecruteak City, and his friend. His friend is seeking out some legendary Pokemon at this location, and Morty has come to help him out. With that information garnered, head northward. For now, pass the ladder by that leads down to the floor below, and do battle with the couple of Firebreather-based trainers ahead of you and to the left. Neither of these guys have impressive parties, but they'll still sacrifice a healthy amount of experience and money when fought, so be sure to engage them both in battle. You should be able to grab an Antidote and HP Up through your first floor journey, as well.
After fighting the trainers and grabbing the items up here, backtrack to the ladder leading downward. The ladder will bring you down to the Burned Tower's basement. When you arrive, you'll see with your own two eyes three of the ultra-rare, mythical legendary Pokemon. They will take a look at you and then take off in a flash, and Morty's friend will tell you that it's a compliment that they seemed to have taken notice of you. Thereafter, you're free to explore this location, but not before fighting your Rival. Your Rival's party is actually fairly strong, with a level twenty Zubat, a level twenty Gastly, a level eighteen Magnemite, and a level twenty-two Pokemon that will vary depending on the Pokemon you took at the beginning of the game. This is a tough fight, and since it's catalyzed when you head into the basement, you may want to consider saving before you go downstairs.
Once your Rival is cleared out, and the legendary Pokemon have escaped for the time being, you can climb back up the ladder and head back outside (without the Strength move, which we don't yet have, it's no use exploring the basement of the Burned Tower, since you can't push around the circular stones blocking your many paths around the room). Return to the Pokemon Center and heal your party. Then, save your game. Following that, you can head to the gym in this city, which is located in the southwestern end of town. There, you will do battle with four "Mediums," Ghost-type Pokemon trainers. Indeed, Morty himself also uses Ghost-type Pokemon. The answer? Believe it or not, the answer is Normal-type Pokemon. If you have Normal-type Pokemon that can use Psychic-based moves (or Psychic Pokemon in general), well then, all the better for you.
The four trainers will be fought, of course, before the gym leader himself. Traversing this gym isn't as easy as it seems, since there's a very thin, linear path weaving around the room. If you fall into the darkness, you'll be transported back to the entrance, so be careful. The trainers all have Ghost-type Pokemon, so try to use Psychic attacks for the best results. Ghost-type attacks are totally nullified if the target is Normal-type, and vice-versa, so keep that in mind and use it to your advantage. For instance, if you use a Normal-type attack, like Quick Attack or Tackle, it won't affect the enemy Pokemon here. On the other hand, if a Ghost-type Pokemon unleashes Shadow Ball on your Pokemon, and your active Pokemon happens to be Normal-type, then you will take no damage. Pretty cool, huh?
The Mediums all have the same three types of Pokemon -- Gastly, Haunter and Gengar. Use the same techniques on all three types of Pokemon. Gastly's insistence on using Curse often can frustrate you, but it will also make your life easier, since half-damage is done to the user of Curse. And of course, you can always retreat out of the gym at any time to heal yourself, save your game, and keep on keeping on thereafter. When you finally get to Gym Leader Morty, you're going to be in for a hell of a battle. Our Noctowl, Togepi and Pidgeotto came up huge here, since the former and latter have resistance to Ghost-type attacks, while the Togepi has Psychic abilities. A similar setup of Pokemon will work wonders for you, but with Morty's ability to use a couple of Hyper Potions during the fight, and with the general difficult slant of this location, be patient, save before the fight, and you should persevere. Your victory over Morty will net you your fourth badge, the Fog Badge, as well as TM30. Very nice, indeed!