Mikey & Don, Party Planners

Ward {2}
You may look at the top card of your library any time.
You may play lands and cast Mutant, Ninja, or Turtle spells from the top of your library. If you cast a creature spell this way, that creature enters with an additional +1/+1 counter on it.

Mikey & Leo, Chaos & Order

Whenever you put a counter on a creature you control, draw a card. This ability triggers only once each turn.

Mouser Mark III

This creature can't attack unless you control another artifact.

Leonardo, Leader in Blue

Sneak {3}{W}{W} (You may cast this spell for {3}{W}{W} if you also return an unblocked attacker you control to hand during the declare blockers step. He enters tapped and attacking.)
When Leonardo enters, if his sneak cost was paid, creatures you control get +2/+0 until end of turn.
{1}{W}: Leonardo gains first strike until end of turn.

The Neutrinos

Flying
Alliance — Whenever another creature you control enters, The Neutrinos get +1/+0 until end of turn.
Whenever The Neutrinos attack, exile up to one target creature you own, then return it to the battlefield under your control tapped and attacking.

Nobody

When this creature enters, return up to one other target artifact you control to its owner's hand. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

North Wind Avatar

Flying
When this creature enters, if you cast it, you may put a card you own from outside the game into your hand.

Food

Pizza Face, Gastromancer

When Pizza Face enters, create a Food token.
Disappear — At the beginning of your end step, if a permanent left the battlefield under your control this turn, put three +1/+1 counters on up to one other target artifact or creature. If it isn't a creature, it becomes a 0/0 Mutant creature in addition to its other types.
{10}, {T}, Sacrifice Pizza Face: You gain 15 life.

Punk Frogs

Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)

Putrid Pals

Deathtouch
Disappear — This creature enters with two +1/+1 counters on it if a permanent left the battlefield under your control this turn.

Raph & Leo, Sibling Rivals

Whenever Raph & Leo attack, if it's the first combat phase of the turn, untap one or two target attacking creatures. After this phase, there is an additional combat phase.

Raph & Mikey, Troublemakers

Trample, haste
Whenever Raph & Mikey attack, reveal cards from the top of your library until you reveal a creature card. Put that card onto the battlefield tapped and attacking and the rest on the bottom of your library in a random order.

Mutagen

Slithering Cryptid

When this creature enters, create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")

Splinter, Radical Rat

If a triggered ability of a Ninja creature you control triggers, that ability triggers an additional time.
{1}{U}: Target Ninja can't be blocked this turn.

Leonardo, Sewer Samurai

Sneak {2}{W}{W}
Double strike
During your turn, you may cast creature spells with power or toughness 1 or less from your graveyard. If you cast a spell this way, that creature enters with a finality counter on it. (If a creature with a finality counter on it would die, exile it instead.)

Tainted Treats

Destroy target artifact or creature. If its mana value was 4 or less, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Teenage Mutant Ninja Turtles