'— Pucey throws to Warrington, Warrington to Montague, Montague back to Pucey — Johnson intervenes, Johnson takes the Quaffle, Johnson to Bell, this looks good — I mean bad — Bell's hit by a Bludger from Goyle of Slytherin and it's Pucey in possession..."
-- Lee Jordan calling a Gryffindor-Slytherin match
Adrian Pucey is a Slytherin Chaser who participated in some of the hardest-fought matches of Harry’s Quidditch career at Hogwarts, including the match where Harry’s arm was shattered by a rogue Bludger (CS10) and the infamous match which ended with Harry, Fred, and George being banned from playing Quidditch for attacking Malfoy after the Snitch was caught (OP19). Pucey was most likely a year ahead of Harry.
Since he was on the Slytherin team during Harry's first year (PS11), he was at least a year ahead of Harry; since he was still there during Harry's fifth year (OP19), he's no more than two years ahead of Harry, assuming he's up to scratch academically.