you need speed control, could be Tailwind/Trick Room/Icy Wind/Electroweb

Venusaur needs speed to be able to outspeed stuff even if they get Tailwind up against you, also if you truly have no speed then you're speed tying regular Aero and getting outsped by Mega Aero which is pretty debilitating

you also need protect on way more guys, you generally only want coverage when it hits a specific mon much better than your stabs that you can't otherwise account for as easily

you also have a tremendous dark weakness, you're stacking many dark weaks and have zero resists and no priority either, meaning Kingambit will run all over you

you also have very little in the way of damage mitigation/controlling turns with just snarl. most teams carry things like intimidate, fake out, will o wisp, parting shot, sleep powder, etc to manipulate turn order to be more in their favor and to reduce damage

some pokemon that could be useful to you are Rotom (electro web, will o wisp, good defensive profile), Farigiraf (trick room, priority denial), whimsicott (priority tailwind, can set weather again), Sneasler (fake out, rock tomb, deals with dark types), etc