Sega Master System / Mark III / Game Gear
To equip Spidey with Venom's suit, start the game in "Nightmare" mode, and after you defeat the Lizard at the end of round 2, move to the right and fall into the pit where you can find the Lizard's key. Then, walk through the sewage to the bottom of the ladder, hold , and press to make Spider-Man dive into the sewage. Press again, and Spider-Man will leap out wearing Venom's suit.
Begin game play in "Nightmare" mode. At the end of the third stage, after you defeat Electro, take the key from between the conductors, and jump down while holding . You'll receive a lot of life.
See the main page for Spider-Man (vs. The Kingpin)