The last thing I need is yet another mobile game that I have to keep up with, so it's just as well that Pokémon Masters is not a particularly compelling game. The game features real-time 3 vs 3 RPG-like combat with the focus being as much on Pokémon as their human companions. As with many mobile games, you have to roll to recruit "Sync Pairs", and you also choose which pairs to level up, promote to higher rarity levels (indicated by the number of stars), and which of their moves to unlock. Some Pokémon can also be evolved.
The game opened to a disappointing reception, although I'm not sure how it's been doing since then. I find the whole experience to be pretty mindless, and the auto-battling feature is the only thing keeping me even remotely involved with it. The developers have been gradually rolling out improvements, and they've started running limited time events in which you can grind to recruit special Sync Pairs (so far Mewtwo, Solgaelo, and Rayquaza). The first event was ridiculously unbalanced and required pretty much nonstop grinding for the duration of the event. The two more recent events have required much more reasonable amounts of grinding to recruit the Pokémon, but still requires a ton of grinding to earn enough materials to fully unlock all their moves, etc.
Super fans of the games or the anime may get a lot of enjoyment out of seeing gym leaders and trainers from across the series' history, but aside from a few of the most famous characters I didn't really remember the majority of them even though I've played most of the games. By now I've recruited a fair number of pairs even though I'm F2P and the Pokémon characters themselves are still fun to see, so even though I'm not very interested in the game itself I'm okay with signing in for my daily log-in bonuses and dropping in for the special events. Although Pokémon Masters has a decent amount of polish, including plenty of voice clips, the story is about the level of most Pokémon games, i.e. completely bland. For me the game is definitely one of the lamer and more mindless spin-offs in the series, and it's hard for me to imagine them adding in any other modes that would change my mind since I find the core gameplay to be so boring.