25 lbs is pretty heavy already for a Miniature poodle mix...especially mixed with a smaller dog like a Maltese! Max is ADORABLE!! If he's already six months, he will probably, depending on his height, only gain another 5 lbs or less.
He looks Shi-Poo to me...Shih Tzu/Poodle mix. I think it's also more likely, considering his size.
I can't wait to see a photo after you've had him clipped! :)