Serebii.net has been taking a hammering since last sunday. It *is* one of the most popular Pokemon sites, and with a million people buying Pokemon in 5 days, there's a chance that a good chunk of them logged on and started breaking their servers. If you can't access the page at any given time, just try again/try later.

But yeah, there are a bunch of old Pokemon you can get in the wild, but it's only afer you see 150 of them and the Poke Radar that comes with that achievement. I learned this yesterday when browsing the 'net to find a Ditto.

Tip I found during this search: To 'view' every Pokemon, just battle Every Single Trainer In The Game. Apparently whatever Sinnoh Pokemon you can't get in the wild, some in-game trainer will have it available for you to battle.