I've been playing around with Ananta in a Venom deck for a little while now. One of the issues is Venom Swamp since Ananta isn't immune to it's counters, so you either Set another copy of Swamp or destroy it.
There are a few issues with synergy, it's true.
Ananta and Snake Rain sounded like a fantastic combination, but the amount of Reptile monsters in the game are very few. It's either "Venom", "Alien", or Gale Lizard and Skreech.
I say make an Alien deck for this. You can probably even go with Balance as the skill, with That Grass Looks Greener and A Cell Recombination Device as some of the only spells in the deck. Not saying it'll be the best, but it'll be better than this.
>I say make an Alien deck for this.
I tried. Ananta feels clunky.
When you Summon Ananta, it takes away all of your resources in the GY for Ammonite, which makes Grass considerably worse, and all of your face-up Reptile monsters on the field. You need to Summon whatever you want to keep on the field after Ananta, but Ananta is going to remove any monster that Ammonite can Special Summon...
You can take away Ammonite, because the synergy with Ananta is just not there, and focus primarily on A-Counters, which would allow you to get Ananta, Alien Overlord, and maybe an Alien Mars on the field. It's decent.