Leonardo, the Balance

Whenever a token you control enters, you may put a +1/+1 counter on each creature you control. Do this only once each turn.
{W}{U}{B}{R}{G}: Creatures you control gain menace, trample, and lifelink until end of turn.
Partner—Character select (You can have two commanders if both have this ability.)

Baxter, Fly in the Ointment

Whenever Baxter enters or attacks, each creature you control with a counter on it gains flying until end of turn.
Whenever you draw a card, put a +1/+1 counter on Baxter.

Hamato Ninpō

Hamato Ninpō deals 4 damage to target attacking or blocking creature.

Leonardo, Worldly Warrior

Affinity for creatures (This spell costs {1} less to cast for each creature you control.)
Double strike (This creature deals both first-strike and regular combat damage.)

Leo's Guidance

Put a +1/+1 counter on each of up to three target creatures. Untap them.

Mutant

Splinter & Leo, Father & Son

When Splinter & Leo enter, choose one or both. Each mode must target a different player.
• Target player creates a 2/2 red Mutant creature token.
• Put a +1/+1 counter on each other creature target player controls.

Splinter, Aging Champion

When Splinter enters, destroy up to one target tapped creature.
When Splinter leaves the battlefield, you and another target player each draw a card.

Triceraton Regenta

Vigilance (Attacking doesn't cause this creature to tap.)
Whenever this creature attacks, untap up to one other target creature.

Wooden Cane

When this Equipment enters, create a 2/2 red Mutant creature token, then attach this Equipment to it.
Equipped creature gets +2/+1.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

April O'Neil, Human Element

Mutagen

Whenever a player casts an artifact, instant, or sorcery spell, you 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.")

Containment Protocol

Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Donatello, Rad Scientist

Vigilance (Attacking doesn't cause this creature to tap.)
When Donatello enters, tap up to three target creatures your opponents control. Put a stun counter on each of them. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Copy

Here Comes a New Hero!

Target player draws X cards. Create a token that's a copy of up to one target creature with mana value X or less.

Donatello's Science Lesson

Tap up to two target creatures. Up to two target players each draw a card.

Donnie & April, Adorkable Duo

When Donnie & April enter, choose one or both. Each mode must target a different player.
• Target player draws two cards.
• Target player returns an artifact, instant, or sorcery card from their graveyard to their hand.

Utrom Monitor

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying (This creature can't be blocked except by creatures with flying or reach.)

Teenage Mutant Ninja Turtles Eternal