Although the rams may be compatible with adult guppies, one or the other of those fish will not thrive in the tank. The rams with a target of soft, low pH water and the guppies with a target of hard, high pH water should be kept in separate tanks. Guppies will adapt to almost any temperature, even a hot ram tank at 27C but the water mineral content will lead to all the concerns that I read about where people think their guppies are inherently weak fish. Guppies are as tough as nails in water that is suitable for them but that water is much harder and much cooler than a ram would find comfortable. Guppies actually do best around 23C but will survive and reproduce faster at 27C. They are also quite comfortable all the way down below 20C.