Between my two save files on Pokemon Diamond, 1500 hours, but that's because I'm a massive nerd. Roughly, I've worked out that I've played that series for around 2900 hours now, excluding the games like Mystery Dungeon and console games.
Not entirely sure on total amount of time because I have restarted each game approximately 3-4 times a piece (I am more for the story aspect most of the time than training the best Pokemon), but I would guestimate around 200 total hours (throughout all playthroughs) per main game (the only games not included in this list are Pokemon Black and Heart Gold), maybe a little under 100 hours for Soul Silver and White because they are the newer games.
The only number I know for certain is Pokemon Conquest at 80ish hours.
The hours that I've seen are preposterous. At most I'd say about 50 hours, that's when I'm batteling every trainer and evenly training my pokemon so no one falls behind. After I sort of lose interest since there really is nothing left after beating the game. That said, I probably just start over if I'm interested.
I cant even start to say how many hours i have put into the series, i know its not a number, sorry, i could check the times on all of them, yes, i still have every pokemon game i ever bought, except for a copy of pkmn yellow and red (i bought that the day it came out when i was 12 ). So for a total i will have to get back, but i know on the original silver for gameboy, i racked up 297 hours and.....47 minutes? Idk if they tell you the minutes, but the hours are right. I looked at people above me and im like, whoa....lol course im 24 and play alot of other games too...