Lightyear Frontier

This achievement can be obtained using only one console, if you have a Game Pass Ultimate subscription and two controllers (one controller must have Bluetooth capability to connect with your smartphone or tablet; it can be either an official Series X/S controller or a third-party one)

You'll need two different accounts, but it's not necessary for both to have the subscription: on the console, you'll use your second profile, while the main account will be used on the XCloud device.

Note: If the profile you want to unlock the achievement with isn't assigned as Xbox Home on the console, you must sign in with your main account (the one with the subscription) to share licenses and online access. Then, log in with the second profile (that you'll use to launch the game).

Once the XCloud session is launched, from start menu select Multiplayer > Host Multiplayer Session, then select a saved game (or create a new one if you prefer, but it will requires more time to unlock the achievement) and skip the password setup using button.

Once the game has loaded, click the button and navigate to "Show Invite Code" to reveal the session code.

Now go back on your console, select "Join Multiplayer Session" from the main menu and insert the code displayed on the XCloud device.

To obtain the achievement, both player must control their respective robots, so on the console after the initial cutscene you have to rush to build the robot. Once both players are inside the robot, use the XCloud device to spray water on the other player to unlock the achievement .

If it can help, I've just unlocked it using my Xbox Series X with its controller and an iPad with the SN30 Pro for Android (don't worry, it works on iOS too).

EDIT As MAJORPOOPY stated in a comment, it can be obtained using only one Xbox controller if you have a model with bluetooth built-in: you'll just have to switch back and forth using the button on the controller (double tap to switch between console and bluetooth).

This achievement can be obtained using only one console, if you have a Game Pass Ultimate subscription and two controllers (one controller must have Bluetooth capability to connect with your smartphone or tablet; it can be either an official Series X/S controller or a third-party one)

You'll need two different accounts, but it's not necessary for both to have the subscription: on the console, you'll use your second profile, while the main account will be used on the XCloud device.

Note: If the profile you want to unlock the achievement with isn't assigned as Xbox Home on the console, you must sign in with your main account (the one with the subscription) to share licenses and online access. Then, log in with the second profile (that you'll use to launch the game).

Once the XCloud session is launched, from start menu select Multiplayer > Host Multiplayer Session, then select a saved game (or create a new one if you prefer, but it will requires more time to unlock the achievement) and skip the password setup using button.

Once the game has loaded, click the button and navigate to "Show Invite Code" to reveal the session code.

Now go back on your console, select "Join Multiplayer Session" from the main menu and insert the code displayed on the XCloud device.

To obtain the achievement, both player must control their respective robots, so on the console after the initial cutscene you have to rush to build the robot. Once both players are inside the robot, use the XCloud device to spray water on the other player to unlock the achievement .

If it can help, I've just unlocked it using my Xbox Series X with its controller and an iPad with the SN30 Pro for Android (don't worry, it works on iOS too).

EDIT As MAJORPOOPY stated in a comment, it can be obtained using only one Xbox controller if you have a model with bluetooth built-in: you'll just have to switch back and forth using the button on the controller (double tap to switch between console and bluetooth).