I changed it to 204 Speed so you can outspeed CS Flygon after 2 Dragon Dances if you get them. But the difference in stat points is because when you boost a nature you receive a 10% boost in points, so for every 4 EVs instead of getting 1 point, you actually get 1.1 on the stat you boosted, and 0.9 on the stat you subtracted. But they only show up every 10 stat points, this is called a "bonus" point. So because Dragonite has the highest base Attack, he will receive more bonus points, because his 1.1 points are worth more in that stat. His speed is his lowest, so therefore he gains the least amounts of stat points. For example, 250 points of speed he can get, so he can essentially gain 25 points with a boosting nature. For attack, he can get to 350, but gain 35 with a boosting nature. Get it?