Beating Culex: The Easy Way

Culex is indeed a difficult enemy to defeat. In order to find him, you must buy Fireworks from the mole in Moleville, then talk to the little girl with her "pwetend" shop and trade for the Shiny Stone. The Shiny Stone will interact with the locked door in Monstro Town.

Culex's difficulty comes, quite simply, from his crystals. He himself has very few moves, and would probably not be an incredibly difficult adversary to defeat. However, his crystals use some of the strongest attacks in the game continually. Such moves as Water Blast, Corona, Mega Drain, Storm, Blast, Blizzard and similar will haunt you. They also have a fairly monumental amount of HP. Thus, if you want to beat him without a lot of levelups and without too much headache, do this: Get yourself the Lazy Shell Armor (the Seed from Megasmilax and the Fertilizer in a secret passage to the left of Nimbus Town) and the Star Egg (win at Look Away about 200 times.)

Now, charge bravely into battle. Equip Bowser with the Lazy Shell Armor before the battle, and get some Pick-Me-Ups. I did this at level 20, so Mario and Toadstool were dead in one turn. But, Bowser with the Lazy Shell Armor (and the Safety Badge or Jinx Belt) takes at most 1 damage from any attack the crystals throw at you! Culex can do about 60 damage with Dark Star, 0 damage with Flame Stone, 0 damage with Shredder (what does that move do anyways?) and about 14 or 15 with a physical attack. If you have 3 Mid Mushrooms, the Star Egg, and 3 or 4 Pick Me Ups, you should be fine. Bowser is an invulnerable tank, but he can't do too much damage anymore. Well, my friends, you have the Star Egg for this reason. Every turn, you use the Star Egg and inflict 100 damage on every crystal. Soon, the Air Crystal disappears, followed by the unfortunate demise of the Ice Crystal, the destruction of the Fire Crystal, and the weakened (usually out of FP) Earth Crystal perishing last. Culex is alone now, with very little health (maybe about 800) remaining. He is usually out of FP. Revive your other two team members and send Culex to an early grave. You can accelerate the process by wasting Rock Candies, but it's not really worth it.

I personally used the Lucky Jewel (since I had the luxury of doing so) so I could double the experience I got. DO NOT MISS THIS OPPORTUNITY! Princess Toadstool gained two levels from this (I had her equipped with the Experience Booster, a luxury you cannot afford with the traditional technique.)