I can't think of any (maybe, winning eleven). you can find tons of 2-players PS2 games, but unfortunately, no good quality party/multi-players game.
I believe the N64 is the best system for these kind of games, followed by the GC next.
good 2-players PS2 games:
Contra SS
Virtua Fighter 4:Evo
Winning Eleven 6
Metal Slug 3 and KOF 2000(Import)
Guilty Gear X
Tekken Tag
Twisted Metal Black
all the shooters ...... and more
just my opinion/taste