can crypto to crypto margin trading run in the decentralized platform?
I think Polo is a decentralized exchange and it allows margin trading for few of the pairs.
Don't know any other exchanges but there are Forex brokers where you can do this, although you will need to get your KYC done before you will actually be allowed to trade there. But why are you interested in crypto-to-crypto margin trading knowing that it is one of the most volatile asset class that could ruin your capital in seconds if a crash occurs? I believe there's no such amount injected in this field yet for such type of trading to be allowed for any class - because it will eventually end up like robbing Peter to pay Paul.