First of all, try not to take VGChartz as gospel, but more like a point of reference.

Pokemon was a series that started out relatively well and just continued to grow. So while '265,000' seems like a small number compared to the millions of the others, it is actually quite a success. It was a brand new game with zero previous franchise support, starting fresh. Take a look at the recent launches of established franchises Mario Kart (594k) and Monster Hunter (880k). The Japanese market is different than it was 12 years ago when Pokemon came out, but still, selling 200+copies of an unproven game is considered a success even today over there.

Pocket Monsters Crystal is Pokemon Crystal. The game they show is the correct game. On the link you provided, note that it was still the top selling game of the week. Perhaps people also bought Pokemon Yellow beforehand, and were like "I'm not going to buy a game like that when I already have Gold/Silver." Also, it was a GBC exclusive game (Gold/Silver could still be played on old GBs) so that could have affected its sales as well.

I can kind of believe the performance bump of FF8. It was the next game after FF7 and they'd gathered much more fans by then, so I guess the hype carrying over from 7 lasted them through 8's launch.

Extra point of reference, Kingdom Hearts 1 launched at 415,445 in Japan, KH2 launched at 740,207. There's no data for the US sales of KH1, but it launched in the US at 719,701 and consistently sold more than it did in Japan after that.