I wonder how heavy ponies truly are. For my headcannon I think they are about 100 kilo's, give and take a little. Maybe Applejack around 115 and Fluttershy about 85. Celestia is around twice the size of a normal pony but I don't think she is quite 8 times the weight. Her build is a lot thinner and more gracile so I think more like 5 to 6 times. Still that makes her around 550 kilo's which is the appropriate weight of a real life horse.