Harlem Heroes is set after the year 2050, when a new sport, Aeroball, which combines elements of football, basketball and boxing, is sweeping the world. The jetpack-wearing Heroes, led by John 'Giant Clay and including Slim, Hairy (who is, of course, bald) and Louis Meyer, are among the best Aeroball teams in the world, until a bus crash kills all of the team but these four... with Louis being left as a disembodied brain in a jar, capable of talking but nothing else. Louis nonetheless convinces his three surviving mates that they must rebuild the team and win the world championship, taking on new recruits such as former reserves Chico and Sammy, the youthful Zack Harper and the grey-haired veteran Conrad King (and later on, Louis the Brain himself in a new android body). But things take a sinister turn when it slowly becomes apparent that the 'accident' which killed the original team was nothing of the kind...
The surviving Heroes returned (as the Harlem Hellcats) for a sequel series, Inferno (set in 2078), in 2000 AD progs 36 to 75, while John 'Giant' Clay (by now the only survivor) eventually reappeared as an old man, the father of Judge Giant, in a Judge Dredd strip set in 2099. His eventual fate would be addressed by Gordon Rennie and Rufus Dayglo in the one-off story Whatever Happened to John 'Giant' Clay? in Judge Dredd Megazine #216, set in 2126.
Second seriesA revived Harlem Heroes strip by Michael Fleisher, Steve Dillon (for the majority of its run) and Kev Hopgood (who drew several episodes) began several years later in 2000 AD prog 671 and ran intermittently until prog 779, before returning for a final stretch in progs 928 to 939. (Siku did the inks for the episodes in progs 933 to 939.) Set in 2190, it featured none of the original Heroes and had a completely new premise (but revived Clay's arch-foe, the psychotic cyborg Artie Gruber).
This version of the team consisted of Deacon, the volatile Slice, tech head Patrice, pilot Trips (who died in prog 694) and the only female Hero, Silver Weir. Though they were still Aeroball players, they were now basically a glorified street gang operating in a world of corrupt corporations. Since the original series is pretty clearly set in the same timeline as Judge Dredd, however, and the second series appears not to be, it's entirely possible that despite Gruber's presence and references to the original team, this is actually set in an alternate timeline.
In 2000 AD prog 1889 Dredd rode past graffiti saying "HARLEM HEROES."