Clear the maps getting the medals not just finish the stage as it's written it suggests that you just have to beat them which is untrue.

For ?-4 putting one fairly strong team to fight the boss and the other 4 teams in the top spawn is the most consistent way to get 3 medals, especially if you make sure the team engaging the boss by the button can't kill the final moth boss as the team heading up the center tends to reach the gate and be sent that way first. Balancing your team 1 to be strong enough to kill the mid-boss but too weak to kill the boss at the end and sending it in the middle will give you more time to make the circuit without worrying about reaching the exit while one of the mobs is still alive, your 2 team should be your strongest provide each team has about 400 speed it be guaranteed be sent around the around once if it gets sent to the right at the random junction on it's first pass. Though all this is pretty moot as just a bit of luck will do and it's not a bad level to grind for seeds.