I don't know if this guy counts as a glass cannon, but he fits being one.
I give you... This guy!
Galvantula can be an extremely useful Pokemon, capable of running many different sets, consisting of special, support, physical or even mixed. Most people give galvantula a focus sash, to set up sticky web 'n stuff like that. Galvantula only has one weakness, which is fire, making it very useful in rain teams. Here is a good set that I would recommend:
Galvantula @ Focus Sash
EVs: 252 SpA, 252 Spe, 4 SpD
Now you may be wondering why this Galvantula has Agility, because he is fast enough. However, when you use agility when your sash activates, electro ball is a must. Bug Buzz is STAB, good power, used when there is a ground type in battle, and thunder is there because wynaut?
Hope I helped!