E.g. If I use sticky web twice , will it lower the speed of the switched in Pokemon twice or not?
I thought of having Smeargle sketch my Galvantula's Sticky Web. Thank You in advance :3
No, unfortunately Sticky Web will fail if you attempt to use it again while one layer of Sticky Web already exists. It won't stack.
Handy little guide for entry hazard moves:
More info on entry hazard moves