This is hard? It's really easy. Just pick on the weakest with everything you have. Rinse and repeat. Only one strategy needed for the whole game. No variation, AI isn't smart. Other, similar games have better features and are more playable.
I never really liked this game but at least in the first one most of the combinations made sense. This game is dull. It is no improvement on the first game. And Internet + Cat still doesn't equal Youtube.
A great game but it just wasn't as fun as the first one. And you shouldn't have to refresh the page after getting all the upgrades before you can finish it.