And Mr Bigglesworth can only be attempted once a week.
Yes and no. You can attempt the raid once per toon per week. What you can do is have someone who has the pets cage them and give them to you. You learn them and get the achievement. Cage pets back up and give them back to the person. Did this with all my friends so they could get theirs.
Looks like Cinder Kitten, Guardian Cub, Nightsaber Cub, Spectral Cub and Spectral Tiger Cub are the only store or TCG obtained pets. That's 5 out of the 25 listed. For those of you that prefer not to spend real money / trade / AH, you wont be able to complete this until you can get Xu-Fu, Cub of Xuen in 5.4.
Update on Xu-fu, the last non-blizzard store/TCG cat pet.
From the front page:
You can purchase the new aspect pets here for 3 x Celestial Coin, which are a reward of the tournament that requires 30 level 25 pets to enter.
Holy crap. 30?!
Any pet achieve hunter will already have 75 level 25's! No excuse for slack!
Your persistence of vision does not come without great sacrifice. Let go of the tangible mass of your mind, it is only an illusion. There is no escape.. For the soul burns on everlasting encapsulated within infinite time. A thousand year journey at the blink of an eye... Humanity is dust..