Alright people, I feel I need to clarify some stuff about what Deku's weaknesses are. Here is a list of things he is and isn't weak too.
Not Weak To
-Shota Aizawa's erasure quirk.
It only works on people with the Quirk Factor as seen in Chapter 135 in the manga. A symbiote is not a quirk and since Izuku is quirkless he doesn't have a Quirk factor, meaning he won't be affected.
-Traditional weaponry
Bullets, knifes and metal bats do not have any effect on Deku. They can withstand a whole lot of punishment and to give an example, you can shoot him point blank with a .50 Cal bullet or shotgun to the face and he'll only be stunned for a few seconds.
-Oxygen Deprivation
You can take away oxygen and he'll be able to survive. Drowning won't work and he can survive a vacuum environment like space.
-Poison
Any type of poison cannot harm them. The symbiote is connected to Izuku's body and can clear out any harmful substances. Even cyanide can't harm them.
What he is weak too
-Fire
Fire can hurt him but needs to be around 2000 degrees Celsius. It won't kill them like Venom, just hurt them a lot. Think of it like being hit by rubber bullets everywhere or something. He can be hurt by Shoto Todoroki's fire and Bakugo's explosion.
If you're confuse then let me explain, pure nitroglycerin can reach temperatures about 5000 degrees Celsius. We don't know if Bakugo's nitroglycerin is pure but for the sake of the fic we'll make it so. (Can't change my mind so complain all you want)
Plus we seen Bakugo melt Todoroki's glacier during the Sports Festival with Howitzer Impact. We can safely assume he can control the temperature of his explosions.
-Sound
The classic symbiote weakness. Must I say more?
-Acid
Acid can cause small damage to the symbiote. Not enough to kill but harm.
-Electricity
The weakest weakness omg the list. It'll just feel like small burns but can still stun him if large enough bolts are applied. Kaminari would be able to hurt him.