To make a Wave in Little Alchemy 2, you need to combine Water and Move. First, drag the Water element onto the playing board. Then, drag the Move element onto the playing board, and place it directly over Water. This will combine the two elements and create a Wave.
You can also combine Earth and Wind to form Wave. First, drag the Earth element onto the playing board. Then, drag the Wind element onto the playing board and place it directly over the Earth. This will combine the two elements and create a Wave.