Greens are less flexible in combo aggro, due to its 2 Gold cost, however they're more durable against low-damage attacks. Greens are still often used in aggro decks; they're often equipped for early-game rushes.
Greens are between the cost of Blues and Yellows, making them somewhat flexible between part of a combo and a solo bloon.
A notable aspect of Greens is that it is favorable for Amelia aggro. Its two charges and 2 Gold are just enough to afford her passive bloon shield (4 Bloontonium), which favors against chip damage.