Mods I'm using are sponge-1.8-1515-2.1DEV-688 and SpongeEssentialCmds-3.0d.
the server crashes occasionally, like after spawning specific Pokemon.
I'm going to attach the logs and crashlogs.
crashlog file: http://pastebin.com/xkHyGVze
serverlog: http://pastebin.com/UNfx78aJ
log when the crash happened: http://pastebin.com/PACQj1Xw