This stage has a shark which can damage your ally knight. However, as long as you can bypass the shark and water, you will be able to pass the stage with stars and furthermore golden crowns. You do not need to kill the shark to pass.

Make sure you equip the following items on BOTH the knight and Maxwell before you rush across the stage.

Set 1: Wings
Set 2: Flying Pegasus
Set 3: Flying Horse

However, if you need to kill the shark for a safe passage, you can use the following:

Lightning, Red Magic, Blue Magic

Scribblenauts Remix 1-10 Cheats Hints gallery:
1-10-1-a: Help the knight across the lake!
1-10-1-b: Electrocute the Water to destroy the sea creature.
1-10-1-c: Use floating objects to cross the lake.