Batallosa is a fantastic piece of Mexican slang that means "troublesome," "feisty," or "hard to deal with." It comes from the word batalla, which means "battle," so someone who is batallosa gives you a fight.
In a spoken line, Chalino Sanchez says of his lover, "Eres más batallosa que hacer gárgaras boca abajo" (You're more troublesome than gargling upside down). This hilarious and vivid comparison makes batallosa an incredibly memorable word, perfectly capturing the frustrating yet captivating nature of the person he can't forget.
Chalino Sanchez is the king of corridos, and this song shows exactly why. It's a story of a love that just won't die, even though it probably should. The singer is completely stuck on someone who doesn't seem to care back. He's spent years thinking about them, crying because he feels his life is extra or unnecessary to them—"He llorado en pensar que mi vida te sobra" (I have cried thinking that my life is too much for you). He tries to forget, but he just can't. He says, "Pero nunca podré, me persigue tu sombra" (But I never will be able to, your shadow follows me). It's this idea of being haunted by a memory that is so powerful.
What makes this song classic Chalino is the mix of heartbreak and tough talk. In one moment, he's dreaming and waiting for this person, and in the next, he drops one of the best lines ever: "Eres más batallosa que hacer gárgaras boca abajo" (You're more difficult than gargling upside down). It's so specific and funny. But the mood darkens as he predicts a lonely future for this person, saying destiny will punish them. He believes they will eventually understand suffering when they find themselves lost and without comfort. It's a bitter pill, but it's delivered with so much feeling.