To get access to four extra levels, tap start "VERY" fast at the "Adventure, Custom Option, etc...." screen. You should hear a chime. You will then have access to four more cool levels in Battle Mode.
Several custom Bomberman parts are scattered throughout the game. Here's how to find them:
Knight Armor - You already have it when you start
Drill Arm - This battle mode item can be found on Black 1. It is at the very end of the 5th room on the median. In order to get there you must fall from one of the platforms, onto the median, and bomb jump your way up 2 more medians. The remote is helpful. Blow up the box at the end of the room and the drill arm is yours.
Tennis Shoes - In the blue resort. In level 1 under the bridge that has a box under it and a blue guy on bridge.
Dragon Head - Green 1 - As shown in the final credit sequence, create a bomb staircase up to the teleporter in the first section. The teleporter will take you to another small room which contains this costume piece.
Iron Goggles - Red 1 - There are three metal doors one the first level, all of which need red bombs to open. This costume piece is located inside the door which is connected to your starting platform. There is a small ramp right before it, so you'll have bomb jump to enter.
Chicken Head - White 1 - On the final section of this level, there is a cottage with a snowman on top, which you need to destroy to reach the switch activating the ski lift. Don't blow up the house. Destroy the snow man with little bombs. Then use the small ledge to create a bomb jump to the top of the house. There will be a small platform to the right of the house with one tree (the costume piece). After getting the piece, fall off the platform to the left (towards the moutain).
Samurai Head - N/A - Beat the game with 120 gold cards.
Dragon Mail - Green 3 - On the first section, you'll notice a teleporter across a bit of water, which you can't reach at first. Get the detonator, and remove all the blocks in that area. Then put a bomb in the elevator (don't detonate it yet!). Then put two large bombs, one on top of the other, against the wall, as close to the edge of the platform as possible. The easiest way to do this is to face the wall and throw the bombs. Then use the elevator to go up, and line yourself up with those bombs. Then carefully walk off and push in the direction of the teleporter. If all goes well, you should bounce off the bombs and into the teleporter.
Iron Armor - White 1 - Go the way of the avalanche. At the very top of the second section is a cottage. Blow it up with a big bomb. On the other side is a tree with the costume piece.
Cat Suit - Blue 3 - After draining the water, it is in one of the pots near the edge, under a bridge (where it was previously underwater).
Cat Hood - N/A - To get the cat hood go to that hole in the building where you can get throw a bomb in to get jems,That is the Entrance! Set up some Bombs that lead from the stairs to this window, you don't need to stack Em. once in the house just steer towards the pot!!
Dress - Black 3 - The instructions to get this piece are actually in the credit sequence. On the second section, there is an elevator block which is seemingly unreachable. Complete the section as normal, and activate the first elevator. Going up will take you to a suspended platform with three planks. Walk of the last plank, and you should fall on top of one of the four sections below. Use a couple small bombs to bomb hop from one section to another, until you find the other section. This secret section is rather large, but isn't to difficult. The costume piece is near the gold card, I believe.
Sunglasses -Black 3 - In the third room, activate switch 4. Then come back and activate switch 3. Use the ladder to get to the platform that is on the right when you first enter the room. From there, make a bomb bridge to the left platform. Take the normal route from there. Use the elevator and go to the next level. You will find a new bridge that wasn't there before. It leads to the Custom Part.
Rocking Horse - Red 3 - Getting to this costume piece is fairly easy compared to some of the others. At the very end of the level, there will be a platform which you need to make fall by destroying the supporting pillars. Before you do that, fall through the hole it will eventually plug. This costume piece should be in a furnace block real close by. Use the tracks to escape the area.
Shogun Kimono - N/A - Beat the game with 120 cards.
Knight Shoes - N/A - Given to you at the beginning
Dragon Spikes - Green 3 - On the last section of this level (with the big tower), on the far wall of the structure, facing away from the teleporter which brought you here, is a secret entrance. It looks like a wall, but you can walk through it. You can find it by pulling the camera in as close as possible, and standing next to the wall. Rotate the camera until it is inside the building. There will be two pots in there, one of which is the Dragon Spikes.
Iron Sneakers - White 3 - Go through the right door once you start. When sliding down the slide, it is in a tree to the far left (opposite side than the switch).
Cat Paws - Red 3 - There is only one metal door on this level, and the cat shoes are behind it. The red bomb is actually in the barrel which is close to the door, but don't blow up the barrel which you need to walk there by accident. If you do, just leave the area and come back.
High Tops - Blue 3 - On Cliff, after first dam (get it beforehand)
Bunny Socks - Black 3 - In the second section, there is a [::] switch. On a wall right next to it are a couple blocks. One of them will have the costume piece.
High Heels - N/A - Beat the game with 120 gold cards.
Knight Sword - N/A - Given to you at the beginning
Dragon Gloves - Green 1 - After receiving the Red Bombs, head towards the second section, and enter the teleporter on the left (which is obscured behind a wall). You will need the Red Bomb to blow up the blue pillars. After going through the teleporter, this costume piece will be easy to find in that room.
Iron Knuckles - Blue 1 - This one is easy. It is in the same room as the switch which opens the exit.
Slash Claws - Red 1 - Knock down the planks to go the alternative way. Near the exit, you will find yourself right above a single block on a short railroad track. kick a bomb off your higher ground, but use the R-button to stop it as soon as it leaves the platform. It should land right on top of the piece. After the explosion, drop down and get the piece. Use the broken tracks to fall down to the bottom level.
Chicken Wings - White 3 - Once first starting, head through the white door. This costume piece will be easy to find, but the strange view might make it seem harder than it is. The costume piece will be out on a ledge in that section, and somewhat hard to navigate to.
Fan - Beat the game with 120 gold cards.
Crazy suit - Beat normal mode with 120 gold cards in under 3 hours.
Gold suit - Beat hard mode with 120 gold cards in under
Get all the Gold Cards then beat Sirius in the Rainbow
Palace. Now go to the Options screen and select Options. Congratulations!
You may now preview the ending and credits whenever you want. You can also
play two new levels in battle mode.
Throw bombs at the butterflies in Blue Resort or the bunnies
in White Glaciers to reveal hearts.
When you see a house with a window open, toss a pump bomb
in the window and wait for it to explode.
To access a sound test option, beat the game in Adventure mode at normal difficulty.