Go to the pet here on WCP. Pick rare. Pick H/H to see power and speed naked, for example. Check with the image or do the math. (I havent done the math - I just filled in the blancks to get the numbers.)
I took the data from the pets on WCP and entered here in a Google-doc with all breeds and ability sets: https://docs.google.com/spreadsheet/ccc?key=0Anwxfm9jABocdDItb1N6QlhvbnMzQVVHQWgtOVBnWFE
It seems like the stats are balanced: if -2 health, it has +1.5 speed and + 0.5 power as example. Even though it looks like some pets have +0.5 to much. (Cinder Kitten, Pebble, some snails...) I have made a power/speed one too.