For the longest time, or at least it seems so, I was stuck with the Advanced Level. There are more beach balls to bust and that Last Mole was impossible to catch. Through some YouTube video, I learned that once you have the puppy to follow you, pressing A sic the dog to the Balloons. It saves you time from having to traverse the distance to bust the Balloons yourself. Just travel a bit toward a Balloon, press A, then the dog will do its job. Be careful not to press A too many times. Press once to get the Balloons busted by the dog, but don't press too quickly or you will call the dog back to you. Another button that is useful to know is the 1 key. In the overview map on the right, pressing 1 will zoom out a little bit to show you where the Balloons are, so you don't end up wandering all over searching for them. Lastly, don't bump into the Moles while they are above ground. You lose points and I think it makes them run away to another hole, making it harder for you to bust the Balloons.
I am now on the Expert Level and it seems to be even more difficult. There are buildings to go around, Balloons may be on the sidewalk or within some place that's higher than the road, thus your progress is slow. I think the trick is to get the dog as soon as possible. Luckily, the dog seems to be in the same spot all the time. In the Advanced Level, it's under the tree on the left if you make the first right turn on the road. In the Expert Level, it's between the building in town. I will try to ignore all the Balloons and go hook up with it next time. That may be the only way to quickly bust all the Balloons, with the dog's help, to have more time to defeat The Boss.