The last mission from level 30 is to duel with Weevil Underwood. I don't know if it is some sort of bug, but the bot appears when I was at level 29... So, now I have the mission (level 30), but the bot appears sooner (level 29). Oh yeah, the bot doesn't appear at the gate.
Answer
Answer List
anoymous
The missions for unlock doesn't appear too. Just say to beat him and I did that at level 29 before to get the mission.
Vlademora
You must unlock Weevil first for him to appear at the gate. Check out these pages: http://duellinks.gamea.co/c/m3z7mu5u
http://duellinks.gamea.co/c/e66qx5jb