Blistoise are able to control how permeable their shells are, letting them reduce the density of the shell surface enough to carry eggs within them. They maintain a perfect environment for incubation within their shell.
The waterspouts that protrude from its shell are highly accurate. If it senses sadness with its fluffy fur, a Blistoise will rush over to the sad person, however far away, to share an egg of happiness that brings a smile to any face.