I would love it if we could have a basket of stablecoins, similar to the proposed index fund.
As for conditions of the badge, does the token need to have a peg? Most stablecoins try to achieve a price target based on stable assets like gold and fiat currencies, while something like Saga (asset backed stablecoins) aims to slowly de-peg once their tokens gain adoption. Limiting the scope to pegged stablecoins though makes defining the conditions simpler:
The token must have a price target (USD, gold, etc).
The token must have a defined mechanism to maintain the peg.
The token price must faithfully follow it’s price target within T period of time prior to badge submission. (volatility limit? perhaps use moving average?)
Perhaps there should be an additional policy for removal? Broken stablecoins should be detected & removed ASAP