Octo-Bomb is just like a Pokey-Bomb but can easily wipe out a base's defense with a champion covering them. Champions like Drull or Fomor should easily destroy a base with the Octo-Bomb. The amounts needed for an Octo-bomb would be the same with Pokey-Bomb since Octo-oozes take up the same space.
For more information please visit the Pokey Bomb page.
The difference would be that the Octo-oozes have a lower attack, so when almost all the defense buildings are down you could send a last wave of different monsters to finish of instead.