MissableHedgie can be found at the entrance of the "Exhibition" during the mission "The Brave New World." As you enter the boss fight arena you'll find a upgrade station and save point. I suggest storing all your firearms (you won't be shooting) but keeping hold of a melee weapon (allowed). Fill the remaining inventory slots with health capsules to keep yourself alive. Run speed and dodge upgrades under the "Character" category are also useful for evading attacks.
To start the boss encounter you need to raise a statue out of the floor using your electric attack
. These are the statues mentioned in the achievement description. Stand behind this first one and Hedgie should charge into it, crashing to the floor and exposing a weak spot. Here you can get a few blows in with the melee weapon hitting the orange nodes. Now we have to try our best to stay alive until we can raise another statue. Hedgie will do various charge attacks which can be dodged
and ground shock waves which you can jump over
. Keep your distance and heal where needed until another terminal pops out the ground you can zap with the Electric Shok. Once zapped another statue will raise out of the ground, use this as cover again to block a charged attack. Hedgie will crash to the ground, where you can hit another weak point. Rinse and repeat this technique until you've smashed all 5 statues and killed Hedgie.
If you failed to destroy all 5 statues during the fight reload your save and try again. Try your best to remember what statues you didn't destroy and target smashing those first as this does seem to be cumulative over multiple reloads. (e.g. First run you destroyed 4/5, Second run you destroyed 3/5 but the achievement still pops because you've destroyed each unique statue).