You can be assured with FJ about sports betting that too with dogecoin. Make sure you go through the TOS before you start betting and if you have any questions feel free to ask their live support or on the FJ gambling thread in the gambling section of this forum. Their staff are pretty quick to respond on the live support though so I dont think you would need the second option.

They often organize betting events with huge prizes so make sure to keep an eye on their thread in this forum.