Bluey: The Videogame

This cannot be in the story objective where you have to freeze the Heeler family and must be done in a separate game (set up using Y and selecting the Xylophone). Easy to do as you just need to get up close to each member and press X to freeze them in place. I believe there is a slight delay so you can't just spam X but the AI are not very intelligent with their movement.

You will unlock a mini game during Episode 4 after you've played the Magic Xylophone game indoors. I finished the main story then done the mini game achievements at the end but you can do them as soon as you unlock each game (there's 4 mini game types).

Start up the mini-game by pressing and selecting the xylophone, you just need to tag all 3 of the other players within 30 seconds to get the achievement.

This guide will walk you through this achievement and all of the other 21 achievements in under 2 hours. Island Rhythms! achievement starts at around 1:44:41 into the video and pops at around 1:45:08 timeframe. All achievement timestamps are shown in the video Description.

This is one of the minigames you unlock later in the game at Episode 4. You will play this minigame as part of the story but that won't count towards the achievement so you will have to do this when you get to the beach at least.

Simply start the minigame by clicking on the Xylophone in your list of minigames in the bottom left corner of your screen, and then once it starts run up to each character and press X to freeze them. Freeze all 3 of them within 30 seconds to gain this achievement. Super easy.

You can follow my video guide below to see how it's done if needed: