Ajani, Nacatl Avenger

+2: Put a +1/+1 counter on each Cat you control.
0: Create a 2/1 white Cat Warrior creature token. When you do, if you control a red permanent other than Ajani, he deals damage equal to the number of creatures you control to any target.
−4: Each opponent chooses an artifact, a creature, an enchantment, and a planeswalker from among the nonland permanents they control, then sacrifices the rest.

Ajani, Nacatl Pariah

When Ajani enters, create a 2/1 white Cat Warrior creature token.
Whenever one or more other Cats you control die, you may exile Ajani, then return him to the battlefield transformed under his owner's control.

Ajani, Nacatl Pariah // Ajani, Nacatl Avenger

Pack Leader

Other Dogs you control get +1/+1.
Whenever this creature attacks, prevent all combat damage that would be dealt this turn to Dogs you control.

King of the Pride

Regal Caracal

Other Cats you control get +1/+1 and have lifelink. (Damage dealt by those creatures also causes you to gain that much life.)
When this creature enters, create two 1/1 white Cat creature tokens with lifelink.

Annie Joins Up

When Annie Joins Up enters, it deals 5 damage to target creature or planeswalker an opponent controls.
If a triggered ability of a legendary creature you control triggers, that ability triggers an additional time.

Feline Sovereign

Other Cats you control get +1/+1 and have protection from Dogs.
Whenever one or more Cats you control deal combat damage to a player, destroy up to one target artifact or enchantment that player controls.

Rin and Seri, Inseparable

Whenever you cast a Dog spell, create a 1/1 green Cat creature token.
Whenever you cast a Cat spell, create a 1/1 white Dog creature token.
{R}{G}{W}, {T}: Rin and Seri deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.