Here's how a couple things work in sideview gravity with classic movement:
1. If Link possesses a ladder, it will be used at just about every tile he comes across if the screen he is on allows use of the ladder.
2. If the top half of a combo is solid while the bottom half is walkable, Link cannot walk through the tile unless the top half of the tile below it is walkable.
However, here's how they work with diagonal movement:
1. If Link possesses a ladder and is on a screen that allows use of the ladder, it will only be used at the edge of a platform.
2. If the top half of a combo is solid while the bottom half is walkable, Link can walk through the tile even if the top half of the tile below it is solid. He can also jump through the top half of the tile, though it requires him to jump twice to get on top of the tile. Thus, it can be used as a 1-way platform.