Evolving Adaptive

Evolving Adaptive enters with an oil counter on it.
Evolving Adaptive gets +1/+1 for each oil counter on it.
Whenever another creature you control enters, if that creature has greater power or toughness than Evolving Adaptive, put an oil counter on Evolving Adaptive.

Repulsive Mutation

Put X +1/+1 counters on target creature you control. Then counter up to one target spell unless its controller pays mana equal to the greatest power among creatures you control.

Grove's Bounty

Distribute X +1/+1 counters among any number of target creatures you control. (Then exile this card. You may cast the creature later from exile.)

Elusive Otter

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Creatures with power less than Elusive Otter's power can't block it.

Elusive Otter // Grove's Bounty

Sharp-Eyed Rookie

Vigilance
Whenever a creature you control enters, if its power is greater than Sharp-Eyed Rookie's power or its toughness is greater than Sharp-Eyed Rookie's toughness, put a +1/+1 counter on Sharp-Eyed Rookie and investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Doppelgang

For each of X target permanents, create X tokens that are copies of that permanent.