The achievement for "get every type of frog on a lead" doesn't require all the frogs to be on leads at the same time. I had some white and orange ones on leads earlier, and I just put a green one on a lead and got the achievement.
Is this intended behavior? Personally, I think the achievement ought to require you to have them all in one place, so the squad is all in one place. That seems like the intent, and it's what I thought the achievement was supposed to be for.
Comparing it with similar advancements, of "collect all variants", this seems intentional; additionally, advancements that require everything at once do specify that in the description (such as How Did We Get Here).