0x supports trades for all ERC20 tokens that are aggregated from our aggregated liquidity sources. Note that the Swap API does not support fee-on-transfer tokens.
To see the tokens that 0x supports for trading, you can refer to the CoinGecko tokenlist. This tokenlist provides a list of all available ERC20 tokens that are supported by 0x. You can access the CoinGecko tokenlist at tokenlist.org, specifically the CoinGecko tokenlist for a list of all available ERC20 tokens.