General Bulborb

The General Bulborb is the first boss encountered, and largest species of Grub-dog in Pikmin Z, twice the size of an Emperor Bulblax, possibly in response to the larger prey items (Titan Pikmin being a prime example) according to the notes. Despite the name, it appears more like the equally ferocious Bulbear.

Biology
This species of Bulborb had grown to gigantic proportions in response to larger prey items. According to the opening cinematic to the boss fight - it shows a few sleeping Bulborbs retreating as it arrives, roaring at them - the General Bulborb will easily attack its own kind, and possibly sees them as food as well. Being a Bulborb, it will slowly follow the player in the area. While slower than a usual Bulborb, it can break out into bursts of speed, which will eat any Pikmin in the way.
 * Diet: small animals, Titan Pikmin (implied)
 * Predators: N/A

Piklopedia Entry
''This gigantic species is the king of its territory. Not even other Bulborbs usually tend to fight this giant beast, and any smaller animal it comes across will easily be devoured no doubt about it. Considering even Red Bulborbs flee from this thing, I can safely say it will eat a sleeping Bulborb or Bulbear if it can get the chance. Don't think a Emperor Bulblax would be on the menu though.''

Strategy
The approach to fighting the General Bulborb is a fairly simple one. Wait until the General Bulborb charges forward to eat your Pikmin, then bolt to the side and let it run past. This leaves it open to attack from behind, and you can flank it. After a bit it will shake the Pikmin off, and jump to try and crush them, so be sure to call them back before it can crush any of your squad. Repeat this process until the boss falls.