Its still unbalanced. The toad Sages need to go along with the hawk and one of the boss toads. Then we have 2 Boss level Snakes vs 2 Boss Toads.
That's assuming that Boss snakes = Boss frogs
Manda would have solo'd both Gamabunta and Katsuyu if the Sannin themselves were not involved in that fight
If i remember correctly, there was a cycle of superiority mentioned. It goes Snakes > frogs > slugs > snakes. As I'm sure you know, Naruto is based off Japanese mythology and legend.
Janken
The world wide game "scissors, paper, stone" originated from China during the Eastern Han Dynasty (25-220), invented by the warlords of that period. Except instead of paper, they used the open palm symbol to repersent cloth, so it's "Scissors, Stone, Cloth". The game reached Japan in the early 1640s and one variation of the game was the "Slug, Snake, Frog" variation.
In this variation, the Frog is afriad of the Snake, the Snake is afriad of the Slug and the Slug is afriad of the Frog. This is influenced by the Sansukumi way of thinking where it keeps the 3 objects in a deadlock. The fact that the Sannins use these 3 animals as summons may be the author hinting that there is no stronger one among them, and that their strength are more or less equal.
I'm pretty sure this was mentioned in the manga but I will have to do some digging.