Multiplayer recommendation for a non MMO/Action game?

The game I’m working on is a 2D pet breeding simulator/dress up game (static images, no moving avatars/worlds) that includes sending messages, auction houses, buying/selling, and leveling/competitions/scoreboards. The challenge in that is all advice for multiplayer I can find includes lobbies and rooms, spawning/enemies/movement, and things that have nothing to do with a game like Love Nikki or breeding sims.

I want this to be an android and ios ap. So I need 3-tier architecture right? Client → Server → Database?
Unfortunately I’m a pro playmaker user so it’s been a struggle trying to figure out even where to start. What 3rd parties should I use, for what reason? What would work best for a game that isn’t an MMO or action?

One suggestion is to look at Photon. They offer async client server data exchange.