This Level allows three butterflies to be on the board at a time.
Get all three down, then build up enough yellow blocks (at least 16) to free all three butterflies at once.
Then, do it all again, drop three butterflies, collect enough blocks, free them and rescue three Pets.
Use the balloon booster you build up in the game to either clear the board of the other colors or to release the butterflies with enough yellow blocks.
To get all 14 Pets rescued you'll need to repeat this 5 times!