The Bomb powerup is a recurring item in the Bomberman series. It increases the player's amount of bombs by one. Bomb Capacity is the amount of bombs a player can have on screen at the same time.
It is advised to set up bombs in such a way that as much floor space as possible is covered. This means "chaining" bombs together, by placing bombs in intersections (a floor tile with a hard block to each diagonal) so that via chain reaction the bombs will all detonate at the same time. To do so, the player must have at least two bombs at their disposal. At least two times firepower is also necessary for efficient bomb chaining. However, when making large chains, players need to take into account the fuse of the first bomb and make sure that they are out of the way by the time the chain detonates. In some Bomberman games, it takes longer for chains to fully detonate, while in others all bombs detonate almost simultaneously.
With at least three bombs, a player can set up an L-shaped trap to attempt to cage in opponents.
Also, the bigger bomb capacity a player has, the less worry that player has about using up all of his/her bombs and becoming momentarily defenseless (bomb-wise). More bombs can also make chaos by either setting, kicking, punching, or throwing them.
It is perfectly possible to win a match or clear (most) stages without picking up a single Bomb powerup. This does make the round more tedious, though, and it is in the player's best interest to obtain as many Bomb powerups as possible, even if his/her bomb count is maxed.
Keep in mind that you will need to have a lot of bombs at your disposal to make good use of the Line Bomb item.