99% of Moto X 2nd Gen. phones for sale on the secondary market are not built for Republic’s network. Republic’s legacy phones (Moto E1, E2, G1, G3, X1 and X2) use modified Android operating systems and were built specifically for Republic’s blended WiFi/cell network. Any previously used legacy phone you were to acquire must be represented as Republic specific and not to work on any other network. Republic offers guidance here: Buying and Selling Used Republic Wireless Phones – Republic Help.
If one is selling a previously used Republic legacy phone, any SIM in the phone should be included. There is no personal or service information on that SIM. Its’ sole purpose is 4G cell data access. In fairness to sellers, including the SIM when selling a previously used phone is contrary to the advice of every secondary marketplace I’m familiar with. Republic’s legacy phones are an exception to the rule if you will.
@michellen is correct that Republic support can provide the needed SIM if the seller fails to do so and that previously used legacy phones activate on these plans: Republic Wireless Plans 2.0: Republic Refund – Republic Help.
@billg is correct that the BYOP Republic SIM you purchased will not work with a previously used legacy Republic phone. That SIM will work only with Republic’s newer 3.0 phones: Republic Wireless Phones – Republic Help.