They raced against the Adder Gang.
The name originated when all seven Sidemen regularly played Grand Theft Auto V together. In order to make things interesting, they split themselves up into two groups. Whilst occasionally working as a team against the Adder Gang, the Zentornos are still very competitive within the ranks. Often, certain members would betray or sabotage their team-mates whilst secretly "working" for the opposition.
The three members of the Zentorno Gang are:
These three Sidemen were generally present in every GTA V video (unlike JJ and Harry) so the numbers were occasionally uneven, leading to certain people swapping teams to make it fair. When JJ and Harry stopped appearing in GTA V all the the time, Simon and Josh would use the Adder in nearly every super car race until the Osiris and T20 came out.
Ethan would also use the Adder quite a lot however he would sometimes use the Zentorno since it's his favourite super car to use. Even today with the rest of the Sidemen exclusively using either the Osiris or T20, Ethan will still use the Zentorno occasionally when he feels like it.
- Zentorno on GTA Wiki
Olajide "JJ" Olatunj