Aah, I've always wondered about this! There's not a whole lot of canon information to base an answer on, but I'd imagine it probably varies greatly between Pokemon species. I wouldn't think most bugs would live as long as, say, dragons. Also, the way it says Absol can live for a century implies that most Pokemon can't, perhaps even that most Pokemon can't live nearly that long, hence why Absol's longevity in particular is impressive.
The species with shorter life spans would probably live at the very least around a decade or so? If their life spans were too short it'd seem kind of pointless to bother training them, as they'd grow old and die before reaching their full potential.
And what about Ghost Pokemon? They're supposedly otherworldy spirits, sure, but you can casually hatch them from eggs. You'd think they'd have to be able to die, otherwise they would overpopulate the world, but it's hard to say whether they work like regular organisms or not.