Genepool Mimic

Biodiversity 1 (Whenever another creature
enters the battlefield under your control, if it
shares no creature types with other creatures you control, put a +1/+1 counter on this creature.)
Whenever one or more +1/+1 counters are
put on Genepool Mimic, you may have it become a copy of another creature except it gains biodiversity 1 and this ability.