I got the mod, installed it right, and in singleplayer every time I try to choose a starter pokemon it crashes my game, and when I made a forge server, whenever me and my friends try choosing a starter pokemon, we get kicked saying "Internal Server Error" and this message appears in the console:

[WARNING] Failed to handle packet for loldogs1337/10.0.0.2: java.lang.NullPointerException

java.lang.NullPointerException

at pixelmon.entities.pixelmon.stats.Level.getExpForLevel(Level.java:81)

at pixelmon.entities.pixelmon.stats.Level.setLevel(Level.java:64)

at pixelmon.comm.packetHandlers.ChooseStarter.handlePacket(ChooseStarter.java:31)

at pixelmon.comm.PacketHandler.onPacketData(PacketHandler.java:55)

at cpw.mods.fml.common.network.NetworkRegistry.handlePacket(NetworkRegistry.java:255)

at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:245)

at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:84)

at net.minecraft.network.NetServerHandler.func_72501_a(NetServerHandler.java:1111)

at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61)

at net.minecraft.network.TcpConnection.func_74428_b(TcpConnection.java:458)

at net.minecraft.network.NetServerHandler.func_72570_d(NetServerHandler.java:141)

at net.minecraft.network.NetworkListenThread.func_71747_b(NetworkListenThread.java:54)

at net.minecraft.server.dedicated.DedicatedServerListenThread.func_71747_b(SourceFile:30)

at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:689)

at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:275)

at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:585)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:482)

at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:582)

Please help! 

Sounds like an issue with Pixelmon not Forge.. go there.