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
Trait: Compoundeyes
Timid Nature
EVs: 252 SpA, 252 Spe, 4 SpD
Moves:
Agility
Electro Ball
Bug Buzz
Thunder
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!