Fecund Greenshell’s last ability checks the power and toughness of a creature only at the moment it enters. If it enters with counters, those counters are included. Static abilities that modify the power and toughness of creatures you control (such as Fecund Greenshell’s own second ability) are also included. If that creature’s toughness is greater than its power when it enters, the ability will still trigger and resolve normally regardless of what happens to that creature after that.