Wouldn't Giant make more sense for the humanoid gargantua?
Probably, but we'll fight that battle when we come to it.
Updated with a few abilities based on comments.
For the sahdow panther, we just went with flavor text:
Shadow panthers have an innate ability to telepathically contact others of their kind whenever they are seriously injured or imprisoned. Even newborn cubs possess this power, which is unconscious and automatic. Regardless of distance, any shadow panthers on the same plane may decide to come to the aid of their distressed kin. If the call comes from a cub the other shadow panthers always form a "strike team" to rescue the youngster and adopt it into their pack.
I don't think the tarrasque's regeneration is appropriate. The original text indicates they only live several centuries (young by dragon standards).
For the deafening roar, we might be able to use some of these kaiju feats for inspiration...
Battle Roar [Kaiju]
The kaiju's roar sounds especially fierce.
Prerequisite: Kaiju template.
Benefit: As a move equivalent action, the kaiju can unleash a battle roar. No two kaiju battle roars sound alike. A creature of 6 Hit Dice or less within 1,200 feet of the kaiju in the round that it roars becomes shaken and suffers a -2 morale penalty on attack rolls, weapon damage rolls, and saving throws. Creatures of 7 or more Hit Dice must make a Will saving throw (DC 10 + half the kaiju's hit dice + the kaiju's Charisma modifier) to avoid the same effects.
Normal: While tremendously loud and unique to that particular kaiju, the monster's roar has no additional effects on those who can hear it. A kaiju roar, under normal cirucmstances, can be easily heard from miles around.
Special: Deafened creatures or creatures who cannot hear are immune to the effects of a kaiju roar. As Battle Roar is a supernatural ability, a bard can user her countersong ability to allow allies within 30 feet to use her perform check in place of the saving throw.
Stunning Roar [Kaiju]
The kaiju's roar is particularly forceful and disorienting.
Prerequisite: Kaiju template, Battle Roar, Thunderous Roar.
Benefit: As a full roundaction, the kaiju can unleash a stunning roar. No two kaiju stunning roars sound alike. A stunning roar has the same effects as a thunderous roar and a battle roar. Additionally, the sheer force of a stunning roar forces all creatures of 7 or more Hit Dice within 1,200 feet of the kaiju to make a Fortitude saving throw (DC 10 + half the kaiju's hit dice + the kaiju's Charisma modifier) or become stunned for 1d4 rounds.
Special: Deafened creatures or creatures who cannot hear are immune to the effects of a kaiju roar. As Stunning Roar is a supernatural ability, a bard can user her countersong ability to allow allies within 30 feet to use her perform check in place of the saving throw.
Thunderous Roar [Kaiju]
The kaiju's roar is unbelievably loud.
Prerequisite: Kaiju template, Battle Roar.
Benefit: As a standard action, the kaiju can unleash a thunderous roar. A thunderous roar has the same effects as a Battle Roar. Additionally, creatures of 7 or more Hit Dice within 1,200 feet of the kaiju to make a Fortitude saving throw (DC 10 + half the kaiju's hit dice + the kaiju's Charisma modifier) or be deafened for 3d6 rounds.
Special: Deafened creatures or creatures who cannot hear are immune to the effects of a kaiju roar. As Thunderous Roar is a supernatural ability, a bard can user her countersong ability to allow allies within 30 feet to use her perform check in place of the saving throw.
