I'll just go with the main gang for now (since I should be preparing for college

)
Littlefoot: Ravenclaw
He's wise and very interested in learning new things. I wouldn't put him in Gryffindor, simply because we would put anyone like him in Gryffindor since we know the Harry Potter cast went there. If I remember the house descriptions well, I'd put him there.
Cera: Gryffindor
Now she's a difficult one. Very stubborn and very courageous at the same time. For the courage part, I'd put her in Gryffindor.
Ducky: Ravenclaw
Once again, very eager to learn and usually afraid. Though I can't say that the meeting with the sharptooth in the original movie wasn't courageous. Both Littlefoot and Ducky could have been placed in Gryffindor as well, but once again I find the lion a bit overrated for this
Spike: Hufflepuff
Can't say much about this. Hufflepuff has always been the 'meh' house in my eyes. Good personalities but no great wisdom or courage, still willing to stand up for a friend. I think he would be accepted very quickly into this house.
Petrie: Hufflepuff
Very loyal to his friends, and scared sometimes. Not so eager to learn as the others (except to learn how to fly, he might do well on a quidditch team

) He'd definitely make the team!