Tier 3 will be the final big challenge you will encounter in How Many Dudes?, and you need to tick multiple checkboxes to succeed. Firstly, qualifying for Tier 3 itself is a huge challenge, and you’ll need to win runs at earlier difficulties.
You’ll also have to gain Gold Stars to unlock the higher tiers. Assuming you have done so, here’s how you can push to complete Tier 3 and defeat the boss.