Turtles Forever

Search your library and/or outside the game for exactly four legendary creature cards you own with different names, then reveal those cards. An opponent chooses two of them. Put the chosen cards into your hand and shuffle the rest into your library.

Raphael's Technique

Sneak {2}{R} (You may cast this spell for {2}{R} if you also return an unblocked attacker you control to hand during the declare blockers step.)
Each player may discard their hand and draw seven cards.

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.

Splinter, the Mentor

Menace
Whenever Splinter or another nontoken creature you control leaves the battlefield, create a Mutagen token.
Partner—Character select (You can have two commanders if both have this ability.)

Leonardo, Worldly Warrior

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

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Bebop & Rocksteady

Whenever Bebop & Rocksteady attack or block, sacrifice a permanent unless you discard a card.

Michelangelo, the Heart

Trample
Raid (the Fridge) — At the beginning of your second main phase, if you attacked this turn, put a +1/+1 counter on target creature and create a Food token.
Partner—Character select (You can have two commanders if both have this ability.)

Michelangelo, On the Scene

Trample (This creature can deal excess combat damage to the player it's attacking.)
Michelangelo enters with a +1/+1 counter on him for each land you control.
When Michelangelo dies, return this card to your hand.

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.)

Raphael, the Muscle

Double all damage that creatures you control with counters on them would deal.
When Raphael enters, create a Mutagen token.
Partner—Character select (You can have two commanders if both have this ability.)

Raphael, Tag Team Tough

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Raphael deals combat damage to a player for the first time each turn, untap all attacking creatures. After this combat phase, there is an additional combat phase.