Follow this guide to find all the 1-ups in Bio-Hazard Battle.
2nd level: After the steep incline you will start to go down. Stay below the track and you will get the first 1-up.
3rd level: After passing the inkblot guys in the jungle, stay towards the bottom. The 1-up will appear just before the incline.
4th level: After the guys that look like lips stay towards the top of the ceiling. When you start going up stay towards the back of the screen and the 1-up will appear.
5th level: At the part when the boulders are shooting up at you stay at the top and the 1-up will appear just in front of you.
6th level: When you are at the 3rd stage of the plane blow it up and then pull backwards. The 1-up will appear.
7th level: When you are going through the part with the pipes and the stuff coming out of them, stay at the back, always charged. The 1-up will appear at the end.
8th level: Just after the mini boss and you are crashing through the walls, stay to the top/back. The 1-up will appear.
To beat the mini-boss in the last level, get a yellow machine gun or laser. Go to the bottom left-hand corner and point it diagonally up-right. The boss can't touch you.
At the ship selection screen, highlight the ship in the upper left-hand corner and press A + B + Start. You will begin as the all powerfull Dragon-bio 5.
Note: There are three versions of Bio-Hazard Battle with different copyright dates. This code is known to work on the 1990 release.
At the level select screen, move the cursor to the last level and press A + B + C + Left. When the screen fades, press A + B + C + Left again. The display will register 5 lives, but they'll never decrease.
Turn on the game. When the Sega logo hold C. When the title screen appears, make a full clockwise circular motion with the D-pad, starting and ending in the Up position. You should hear a noise if the cheat worked. Release C and press Start to choose your level.
At the main menu, highlight the 2 PLAYER option, then hold Right and press Start. Don't release RIGHT until the ship selection screen appears. If your timing was right, both players will have the upper-right ship selected.
In the caves just past the guys that look like lips, go up to the upper left-hand corner. You will die and begin in a new level in a giant asteroid field. When you finish the level, you will return to level 4, the caves.