Despite occasionally being at odds with each other (particularly in the earlier episodes), 002 and 004 often display great teamwork in battle. Even when they first met ("Black Ghost Lives"), they worked amazingly well together.
When 004 battles a robot replica of himself, they fight so intensely that the difference can't be seen between the two — but when the robot knocks down an innocent bird's nest in one of its attempts on 004's life, 004 catches the nest and shields both mother bird and babies with his own body, proving that he is a human and not a machine. Also a Heartwarming Moment (the manga equivalent is a little more bittersweet).
001 gets a chance to shine in his psychic battle against the cyborg goddess Hera.
003 gets hers when she almost single-handedly hijacks a plane to stop some mafia groups from releasing a deadly virus in Cairo. Defeating several guards without spilling a single drop of blood and disarming the bomb on her own, without any guidance from Gilmore? Awesome.
GB aka 007 gets a massive one when he uses his powers grow MANY times his size to protect himself, 006 and 009 from a stampede of cybernatically-enhanced animals. It's both awesome and hilarious thanks to him going Large HamandBoisterous Bruiser, too.
In that same episode, to attack another group of enhanced animals, 004 leaps into the air... and uses both of his leg cannons at the same time.
In the 2001 anime episode "Frozen Time", despite him nearly Going Mad From The Isolation because of his predicament, 009 makes use of it to single-handedly prevent a truck's explosion near Chang's restaurant from killing bystanders, including a little girl 007 attempted to save. This also doubles as a Heartwarming Moment.
005 standing alone against what is basically the Spirit of the Earth itself to prove humanity's potential for good. He gets beaten down, but keeps fighting because he believes in humanity despite all the pain he's gone through from humans. The spirit leaves in defeat.
A Black Ghost example where in episode Friend a blind Black Ghost assassin manages to fatally strike 0013 with his cane sword by honing in on the sounds he generated while in Acceleration Mode despite 0013 being faster than 009 and moving at light speeds. Certainly a supremely badass moment for a minor character.
Manga
004's battle with the robot replica is a bit darker in the original manga story "The Bizarre Machine", with the fake 004 brutally crushing the nest of baby birds beneath his foot, then murdering their mother. But in the end, the real 004 manages to get the upper hand over his replica due to that distraction, and shoots it full of bullets, remarking that his lingering humanity and "weakness" is what proved him to be stronger than the robot.
