EVs: 252 Defense, 252 S.Defense, 6 S.Attack/HP/Attack
Protect(HP EVs) or Attack-order(Attack EVs) or Hidden-power(Ground)(S.Attack EVs)
Defend-order makes you very bulky after a couple of uses making this bug hard to take down without a Rock type move. Heal-order is reliable healing. Toxic is status. Protect is for awesome poison-stalling, it even helps with Pressure-stalling, Attack-order would be for Physical STAB while Hidden-power(Ground) would be Steel and Poison type coverage. The main problem Vespiquen has is that it has terrible typing for a wall, you are going to have to watch out for Rock types, Stone-edge is your biggest issue as it has high critical chance and criticals ignore your stat ups, if you come across a Pokemon with Stone-edge either get out of their or try to Pressure+Protect stall them into running out of Stone-edge PP and hope they miss between turns(switching is better though).