Final answer:
The significance of Felix the champion vs Antonio the challenger in 'Amigo Brothers' is that Felix represents friendship, while Antonio represents rivalry.
Step-by-step explanation:
In the story "Amigo Brothers," Felix and Antonio represent friendship and rivalry, respectively. This is represented by their roles as champion and challenger. Felix symbolizes friendship, as he continuously supports and encourages Antonio, even during their boxing match. On the other hand, Antonio represents rivalry because he wants to win the match and prove himself as a worthy opponent to Felix.