Informal:
* Che amígo: This is the most common and informal way to say "my friend," suitable for close friends.
* Che amiga: If your friend is female, you would use "amiga" instead of "amígo".
Formal:
* Che amigo/a: This is a slightly more formal way to say "my friend" and can be used for acquaintances or friends you're not as close to.
Other options:
* Che kuimba'e: This means "my friend (male)" and is a more formal option.
* Che kuimba'e: This means "my friend (female)" and is a more formal option.
It's important to note that the gender of the noun "friend" in Guarani is determined by the gender of the person you're referring to.
So, depending on the situation and your relationship with your friend, you can choose the most appropriate way to say "my friend" in Guarani.