Do your best to avoid shooting the Skywhale.

Run to one end of the platform at the beginning. When the Skywhale reaches you and drops Kamikazes, immediately run to the other end of the platform. As the Skywhale turns around and meets you again, run to another end and clear Kamikazes which stand in the way. Repeat.

It helps minimize damage to the Skywhale.

Jump again immediately after you jump and land on a platform. It saves your time and can magically avoid most crashes from Kamikazes.

Make sure you have 21 or more sec left at the checkpoint. If not, restart the challenge. It's almost impossible to finish the second part of the challenge with less than 20 sec left.
* For Challenge 11, you need to meet one more condition: Reaching the checkpoint with no more than 3 Kamikazes chasing you.

Always keeps your health above 30%. (That's the health you left after being stomped 3 times with full health)

Deal with Kamikazes with Tesla Attack.

When they are flying through the stompers, use it to freeze them.

Right after the challenge starts, double jump to the left border of the scene. There you'll stuck in the wall and nothing will attack you.
Take a rest and wait for victory.
* Works in Ver. 1.15. It may be fixed in future updates.

Jump to the top left corner. Dealing with enemies and lasers from there could be easier.
Just be careful of the trains.

Most gold challenges can be completed with enough practice.
Every time you fall, stand up and start again!