In my opinion, platies should never be kept in a 10 gallon and they need to be in a school, not just 2. That goes against what a lot of care sheets might tell you but from my experience, they really thrive in those conditions. And they especially need larger than 10 gallons if you house them with other fish aka a community tank. No community tank is suitable in a 10 gallon aquarium, doesn't matter what species of fish you stock it with.
I use to breed platies as feeder fish for my other larger fish and the other fish I bred. Despite them being just feeder fish, they still got a great life and I got to experiment with them a lot. I've tried them in 10 gallons, I've tried them in small groups. But they do especially well and act more vibrant when housed in a larger tank (about 20 gallons) with a school sized amount (a school of fish is typically 5 or 6 fish minimum). Their personalities really come out when they're happy and comfortable. Platies are a truly rewarding and extremely undervalued species in freshwater aquariums. They really make great pets.
I can't speak for the other species as I have never owned them but, I agree with noseless. Your tank readings would not be 0 on everything if it were a working, cycled tank. Either your tests are very inaccurate or you have a brand new tank that has yet to go through it's cycle. If it is a new tank, you're bound to have off the charts readings in the near future and many fish will die as a result before it stabilizes. Neons are especially impacted by an uncycled tank as they are sensitive fish that require an established aquarium before being introduced. This is why you should always stock a tank as low as possible when making a brand new tank or preferably do a fishless cycle first. In a working aquarium, there would be a reading on nitrate at least, it's inevitable. Even the dreaded ammonia can be common to get a very low reading on in a cycled tank.