how do you increase your pets stats like strength,speed and such?

You can train your pets and raise their stats at the Training Center. I think there are other ways, like giving them items or something, but I think that training them there is the simplest way to do it, and the only way that I actually know of~ XD

thank you ^w^

The stat boosting item list is here by the way http://www.subeta.net/forums/view/365840 :)