Full Bloom says "Counts as Overgrowth." Does this mean it has the same text as Overgrowth in terms of a Monster getting to act twice? Or just that it triggers Monsters that care about Overgrowth entering or being in play?
The latter. Full Bloom doesn't have Overgrowth's text, but monsters that are empowered by Overgrowth are empowered by Full Bloom as well.