In Super Mario RPG Remake, you can rematch against the bosses after completing the game. There is also a secret final boss called “3D Culex”. Before reaching the secret final boss, “3D Culex,” you need to complete the game first by defeating Smithy and 2D Culex.
Finding and defeating 2D Culex is a must, if you want to find the final boss 3D Culex after completing the game. To find Culex both times, you need a special item. Below you will find a brief guide on how to get this item and fight with the final boss.
Super Mario RPG Remake How To Get Secret Final Boss 3D Culex & Rewards
To fight with 2D Culex, you will have to reach Monstro town. In Molevile you will find a stack of wooden boxes. Hidden behind the boxes, you will find a mole who will trade a Shiny stone for fireworks. To obtain fireworks, visit the house marked in the image above, and inside, you will find the mole who will trade fireworks for 500 coins.
After obtaining the fireworks, trade them with the shiny stone and visit the middle area of Monstro town with lots of doors. One of the doors will be a bit darker in color but has been sealed. You can open the seal by using the shiny stone, and inside, you will find 2D Culex.
After defeating 2D Culex, progress in the game until you beat the main boss Smithy, and the post-credits will roll. After that, you will be able to explore all the areas again and rematch with bosses. You will find Belome in Belome Temple, Punchinello in the mole mines, Booster in Booster Tower, Bundt in Marrymore Chapel, and Johnny in the sunken ship area.
After defeating Johnny, you will obtain the Extra Shiny stone only if you have defeated the 2D Culex before completing the game. Now, visit the same door in Monstro town where you fought with 2D Culex. There you will find the final main boss, 3D Culex. Defeating 3D Culex will be much harder than 2D Culex, and once defeated, you will obtain an item called the “Crystal Shard.” Take this shard to the frog sage in Tadpole Pond, and you will be honored as Mario Sage