I found that setting Resource Pack to prompt(Click on server, goto edit), instead of Enable. And accepting it in the game while entering pokeworld works!. So far it has worked for me 100% of the time.
optifine doesnt work for me but if you allocate more RAM its the same so i need to download forge > put in optifine there > boot up game > (obviously i had to do other things too) > and then it worked so i recommend doing that