Okay, so this may not be a popular opinion, but no electric scooter is waterproof.
Yes, some have IP ratings and most are very well sealed (or can be by very savvy customers), but even a water resistance rating is just that -- how well a product can avoid damage (not escape it).
Quite a few of our electric scooters carry high IP ratings. That means the manufacturer went through the process of seeking and obtaining certifications to demonstrate their products are protected from some level of (primarily) water exposure.
Other scooters that don't have IP ratings aren't poorly made (if you've seen a Dualtron in person, you know); the manufacturer just didn't get the certification.
IPX6 is one of the highest ratings (EMOVE Cruiser), and it basically means the scooter is protected from "high-pressure jets of water being sprayed at it from any direction".
However, that doesn't mean it can wade through water and live to ride again -- unless well taken care of.
If you do get caught in the rain, get your scooter as dry as you can once indoors, and check where you can (without voiding the warranty) for water damage/exposure.
Maybe you can ride regularly in the rain as long as you make sure nothing gets damaged, but I haven't tried it.
What's your experience/advice about riding an electric scooter in the rain?