Level 22 Grrrrrrrr... For those like me having trouble with it... heres the solution: Skip the green button when going right (bounce on the koopa -> jumppad -> red button). Then get the flying mario in to the green hook-like formation. Go back with the other mario for the green button and fly to the coins!
Nice game! For those having trouble with the "Tools of the Trade Badge" the following resource management works fine:
Level 1: 1 Sentry (get it out rightaway)
Level 2-9: 1 Sentinel
Level 10: 1 Beam Surge (wait until they are fairly close)
Level 11: 1 Sentinel
Level 12-14: 1 Sentinel & 1-2 Repulsor (might be level 12-13, cant remember)
Level 15-19: 1 Sentinel & 1 Beam Surge
Level 20: 1 Sentinel & 2 Beam Surges
Add a repulsor burst here and there for safety if you are failing, but it shouldn't be necessary.
 "Enough Plumbers"){kind=icon}
 "Desert Moon"){kind=icon}
 "Epic War 3"){kind=icon}
 "Elements"){kind=icon}
 "AdVenture Capitalist"){kind=icon}