It is not advisable to move freezers on their sides. It can disrupt their internal mechanisms, cause coolant leakage and lead to damage to the door especially if it swings open during the moving process and suffers torsion of its hinges.
When a freezer is moved, it should be emptied out. No food should remain inside. It should also be defrosted if at all possible to ensure it doesn't leak during the move.
Freezers and refrigerators should also never be laid on their backs. The delicate heat dispersion elements on the backs of cooling chests and freezers can be crushed easily if they are placed on their backs.