
If you defeat him, you get back the Striker and he'll join the party.
After rescuing Shadow from the cave on the Veldt and getting the Striker, bet the Striker and you'll fight Shadow. Usually, however, Typhon will sweep your character out of the arena with its Sneeze attack and you'll win nothing. Betting anything not on this list will usually pit you against Typhon, with an Elixir as the reward. The table below lists what wager gets what. Your opponent and reward for victory is determined by what item you wagered. You may want to save right before each wager and reload that save if you lose. Either way, you don't get back the item you wagered. If your character wins, you get a different item. The fight is automated you can't control your character, so just make sure to give them your best equipment beforehand.
Wager an item, then pick a character in your party to fight one-on-one. In the World of Ruin, you can visit the Dragon's Neck Coliseum and bet items to get new equipment.