Tip for the last stage, the part with the plunger shooting kangaroos.
They take 2 hits, but you can damage boost through them if you make it to them with all 3 hearts. Also, they can be insta-killed by hitting them as they appear on screen (its very weird timing).
Finally for last boss "The Fat Cat", easiest way to dodge his attack is everytime you hit him, run left and jump up and over his ashes back to where the ball lands. )In an arc shape.)