All of these CPUs are pretty bad for gaming, and FM2+ is a dead socket with no new CPUs coming and thus no upgrade potential.
The A4 is a single-module CPU, not quite a full dual core - the two cores share resources and if they're both in-use, performance suffers. Each core is similar in performance per clock to a Core2Duo, which you could have picked up circa 2005-2008.
The A6 and A8 are dual module CPUs, not quite complete quad cores - if more than two cores are in use, there's a performance penalty. They perform about the same per clock as a Core2Quad, circa 2007-2008.
Most games these days are starting to need at least 4 hardware threads to run well, and in a handful of cases, an A4 would not even be able to load some games. If you're playing only MOBAs and older titles you'll be alright. The A6 and A8 will do better since they have more cores, but because of how slow each core is, you'll find the more demanding titles will perform poorly.
Food for thought: Intel's $60 Pentium G4560 greatly outperforms any of them while using half the power, and is on a current socket which will be receiving new CPUs. You could drop in a Core i5 or even i7 later if you find performance to be lacking, whereas with the AMD chips, you'll need to replace the motherboard and RAM too, since there are no upgrades.