The Coliseum is a mini-game in Angry Birds:RPG.It's like a survival mode where you get to fight many monsters.Orange Bird does not earn any EXP in the Coliseum.He can only be by himself and nobody could fight alongside with him.
Orange Bird earns medals for killing a certain amount of enemies.Here are the medals:
Rock Medal - Kill 100 enemies.
Iron Medal - Kill 175 enemies.
Steel Medal - Kill 250 enemies.
Copper Medal - Kill 475 enemies.
Silver Medal - Kill 580 enemies.
Titanium Medal - Kill 750 enemies.
Gold Medal - Kill 835 enemies.
Waves are a huge pack of monsters that are fought when Orange Bird reaches 1000 enemy kills.Waves of monsters are very hard to eliminate, depending on their level and stamina.Once you killed about 500 enemies more, Orange Bird will earn the title,"Arena Champion."