So I just beat Erick yesterday, and I came up with a fool-proof plan, and it worked! Granted it was on Normal difficulty, but it works with Intense as well, with one slight problem. The main Pokemon I used for my plan were Pyukumuku, Wishiwashi, Seaking and Shedinja. I used Pyukumuku's Purify to change Murkwater to Water Surface, Seaking's Lightning Rod to avoid any Electric Attacks, Wishiwashi's Dive to change field to Underwater Surface, and Shedinja to take care of the rest. Shedinja's Wonder Guard resists every attack on Erick's team except Electivire's Fire Punch and Eelektross' Flamethrower, and Underwater Field negates all Fire attacks so Shedinja is untouchable. The same will work for Intense difficculty, though you'll need something to take out the Oricorio so Hurricane won't kill Shedinja. So all you need is to change to Water Surface, then Underwater, a Lightning Rod to protect the first two, and Shedinja, preferably with Dig.
