Pixelmon DOESNT WORK?!?

Guys i recently tried to launch pixelmon 4.2.5 with minecraft 1.8.9 and my game crashed it said to me that im using an unsupported version of the game and it didnt let me to copy the crash report :/ WHAT CAN I DO? I have to figure out a way playing pixelmon either on 1.8.9 or 1.8 or 1.7.10 in a version that i can find and doesnt crash or has like massive fps drops... my pc can run normal mc with around 300 fps but only 100 with the 4.2.0 version that i can launch with the Pixelmon Lancher Programm.. Though i NEED the mod itself so i can put it in the mods folder of my server eitherwise i cannot play in my server... PLEASE HELP