So,
@Altari_owl, I'm a little confused about the moves being used. For Camouflage, why would it change the Pokemon's ability to climb uphill? The path they will be racing on is, I believe, flat ground that has sharp twists and turns and is steep as it is going uphill. Plus, Camouflage just changes the type, not the capabilities the Pokemon has, so just a little confused by that.
Sunny Day and Leech Seed are actually very clever though, but I'm confused why the vines would be used. You have to follow the path, and you can't scale the mountain without staying on the path. I'll let Captain Cardboard decide if there's shortcuts, but from what we have discussed before in the first two pages of this thread, we have to follow the path and can't skip large parts of it.
As for Horn Leech, how would it be used for aerial maneuvers? Yes, you will be going uphill, but why aerial movement? I would assume you mean to allow your Sawsbuck to steer on the sharper turns, but I have no idea what you mean by aerial maneuvers. XD