“Wallie” is a trick named by combining “Wall” and “Ollie.” As the name suggests, it uses a sharply sloped bank or wall to create a floating sensation similar to an ollie. The key is not to actually ollie, but simply to ride through it. You can land it even if you cannot ollie, but you do need the level of stability that allows you to do Ollie.
STEP BY STEP TIPS
1. Approach

Wallie takes a bit of speed. If you go too slow, you might get stuck and it can get sketchy. So commit, go in with some speed, and approach it straight. Keep your back foot on the tail.
2.Let the board ride up the bank without doing an Ollie.

Basically, it feels the same as riding through a mellow bank without doing an Ollie. Instead of popping the tail or forcing the nose up, focus on reading the slope and letting your board follow it as you push through with some speed.
3. Keep your balance point on center

You are not actually doing an ollie, but you should pull your upper body upward as you enter the bank. At the same time, keep your weight centered over the board to avoid getting thrown off when you land. Start with a slope around 45 degrees like in the video, and once you get the feel for it, try taking on vertical walls with the same approach.