Denied, you can simply choose same team as your mate(dont spawn as 'No Team') and use
/nogoto 1 so that your mate can use
/goto. If you just want to duel, then choose different team or 'No Team' and use either
/spawnloc or
/diepos or even
/duel command which are more suitable than
/goto for dueling.
Notes for nogoto options:
1 - Only allow clan mate and team mate(unless you spawn as 'No Team') to teleport to you
2 - Only allow clan mate to teleport to you
off - Allow all players to teleport to you
The reason we removed commands like /team is because same thing can already be done using commands with similar function..