Original R/B
Good - Started it all. And I love the concise 151 and the question of what will come next, as there was nothing to base it off of. I'm not a genwunner, but my favorite region.
Bad - It was a hassle to catch 'em all, as the game was advertised, and I guess it didn't age well. THe random enounter rates could have been lowered too.
Yellow
Good - Again, easy 151 pokemon. And now you can get all the starters and follow the adventures of your childhood hero, Ash Ketchum!
Bad - Pretty cheesy, and the same flaw as R/B
S/G
Good - I loved the new pokemon.
Bad - The level curve is so obvious, and the fact that almost no gym leaders have a gen 2 pokemon as an ace angers me. I don't like gen 2 at all.
Crystal - never played
R/S
Good - My second favorite region. I love the new pokemon more than anything and how great the replayability is.
Bad - I guess too much water?
FR/LG - never played
Emerald
Good - See R/S, plus Battle Frontier.
Bad - I'm honesty not sure. While I said too much water before, Emerald's story and interesting water encounters tone down the annoyance. My favorite pokemon game by a large margain.
(Forgive for any wrong order past this point)
HG/SS
Good - I loooove the new minigames and mechanics.
Bad - See S/G, although it was helped a bit, stil unbalanced.
D/P
Good - Decent animated sprites, finally! And I love the new designs.
Bad - I hate the storyline. Completely overshadowed by B/W. My least favorite games
B/W
Good - FULLY ANIMATED SPRITES YES YES YES and an amazing storyline. N is amazing, the only truly good rival in my opinion.
Bad - Too many exclusives, and I don't like the way the difficuly mechanic was added in.
B2W2 - never played
X/Y
Good - Decent storyline, love the new designs, great jump to 3d. The best addition is definately Mega Evolution for me, though.
Bad - Team Flare. 'Nuff said.
OR/AS
Good - I'm way biased towards gen 3 games, but still. I think the characters were well-handled in 3d, and see R/S.
Bad - TOO MUCH WATER!
S/M
Good - I like the Hawaiian asthetic, and the colorful menus. They took a lot of risks here and I think it payed off. You can start to see 3d being entertained more and more.
Bad - Trials and ride pokemon just don't cut it.
US/UM
Good - They covered a lot of plotholes with this one, like where Kahili came in.
Bad - I don't really like the warp ride. Cool idea, not really well implemented.
LG P/E
Good - Finally overworld pokemon! I might be labled a genthreer, but this would be a perfect pokemon game if not based off gen 1.
Bad - See R/B
Sw/Sh
Good - Wild area, great DLC, amazing new designs.
Bad - Pretty much everything else. Seriously, Gamefreak? It feels SO rushed.
If I missed any, tell me.
