005- video/action for Violet City- post Fourth Wall event

So....I've finally arrived within Violet City after a long trek with Snake and our Pokémon. It took time since there was a lot of grass and quite a few wild Pokémon, which kept springing up at us. Does that happen to everyone?

I'm lucky I have such a supportive team on me, otherwise I know I would be stuck or worse. [He is also grateful that he's travelling with Snake, otherwise he'd be worse than lost. He's now looking upon Violet City's gym and wondering.]

Does anyone know what a Pokémon Gym does or what happens within it? I've got the basics about battling now but I'm still unsure about Pokémon Gyms. Do you have to train your Pokémon up quite high to challenge the leader? Is it like an ordinary gym where you work out? If someone could answer my questions I'd be grateful. I'm probably nowhere near gaining a badge at all but my curiosity has got the better of me, now that I'm actually within my first big city. [And....wasn't it big? There were lots of shops, houses and people. Not to mention a large looking tower off to the distance.]

Also, does anyone know what the large tower within the city is? I might want to take a look. [Don't get lost, Otacon.]