Great Nature-Polaris

The immediate problem I notice is that Ponga is an absurdly techy choice. He can work in a build like Leopald, but Polaris takes a ton of set-up to get good, so you really do need Bison to hold the game out.

The second problem that comes to mind is the lack of Monoculus Tiger. You'll need at least 2 of those, since it's another out into your combo. He'll swing for the same unboosted under Polaris's buff as would Compass and Binoculus under the same boost assuming an 11k vanguard, and is only barely topped by Compass against a 10k vanguard, plus he'll give you the same bonus Binoculus does. I'd swap the Sloth Tanks for him. Bison does the same job, but slightly better, since he's going to be the guy you sit on until you're ready to go Polaris.

I might also replace 2 of your Eraser Alpacas with Castanet Donkeys to get you to the start the combo quicker, but that's more to preference.