Win your duel to climb an arena, lose and you drop one. Every arena gets a random weapon: sword, boxing gloves, spear, hammer or bow. Most wins after 6 rounds takes the cup.
Bots
Tournaments against bots give XP and coins but don't count for the leaderboard.
Join a public tournament with anyone online. Up to 8 people, empty spots are bots. Online tournaments with 2+ people count for the leaderboard.
Or play with friends
On a phone: turn it sideways. Left stick moves (up = jump, down = guard), buttons on the right fight.