Another short tip:

The rule of threes is very obvious in most boss battles, but the rule of seven is less so. I’ve outlined a simple one below to get you started.

STAGE 1 – SHOW THEM WHO’S BOSS

1. Intro – Pause. Audio: “IGGY KOOPA!”

2. Teach – Iggy runs left and right. Bounce on his head once.

3. Surprise – Iggy leaps away and becomes invincible for a bit.

STAGE 2: UP THE ANTE

4. BAM! – Two “hologram” Iggys appear and run left and right.

5. Repeat – The player must show they’ve mastered the trick.

STAGE 3: FIRE THE BOSS

6. Defeat – Iggy flashes and disappears in a cloud of stars.

7. Reward – The player rescues Toad.

More in-depth: https://www.gamedeveloper.com/design/boss-battle-design-and-structure