After a few frustrating efforts at the train and beating Shao, I've come up with a way to kill her for Zero buy Maplestory 2 Mesos that should lead to no passing (it did for me personally, twice in a row,) and a couple(somewhat obvious, but still potentially helpful)hints for penalizing the train. Most of the depends on the skill "Time Holding" so in case you are too low to have this ability, this might not be as helpful, but you still might find a few tips.
Always head to the left as that is where the final car is and the explosions you have to escape from start on the right side. Stay on the top for as much as you can as there's less things to obstruct you and allow the explosions to grab up to you.When you need to go down, simply jump close to the edge of the surface of a vehicle and you should get inside the next one.Don't kill some of these monsters, just repeatedly press on your potions and walk beyond them.Make sure you have your "Rewind" on in the event that you're high enough to possess it. Should you make a mistake along with the explosions have been in opinion, utilize "Time Holding" and attempt to get as far ahead of them as you can.
(She can teleport before you, occasionally, so if you have "Rewind" I do recommend having it on, just in case.) If she teleports, instantly press double up-arrow onto one of those (apparent, no enemies on it) above platforms. Wait until you hear four (4) explosions. That is when you know that there's no more any leaf bugs down below. (The leaf bugs will kill you inside one hit.) Jump down and continue attacking. Repeat this till she starts spawning her giant fire charm.
When she starts spawning Maple M Mesos her giant fire spell, immediately press "Time Holding" and press on double up-arrow to get on top of one of the high platforms, just like before. Wait until it finishes, and leap back down. Repeat the first four (4) measures until she's dead. I hope this is useful to anybody stuck on Shao. I could not locate some additional guides about this.