Generation V. I find it hard to even play through that game at all. And you're pretty much forced to use your starter in the beginning because Lillupup, Patrat, and Purrloin are probably the worst pokemon you could ever have. Pidgey, Hoothoot, Gastly, and Ralts are all easily obtainable and decent. So why do I have to use Purrloin, which learns its first Dark move at level 15, while I'm stuck using Fury Swipes and Scratch until then. And don't forget that every five minutes Cheren, Bianca, or N have to challenge you to a battle until you've already battled them all five times and you're barely at the second town. Or Alder forgets to give you, the most important berry of all, the Oran Berry. Yeah, I'm really gonna be using Oran Berries when at this point I can buy Potions and Super Potions.
To the above poster, you really have to critique HGSS. Obviously if you critique GSC under the present-day eye, they're going to look terrible, but they were incredible for their time. Things changed in Pokemon, obviously those games will look bad compared to something like DPPt.