The second member of the Elite Four is Grimsley, who excels in using Dark-type Pokemon. When you talk to him after beating the main story, he will tell you a metaphor about life: use the cards you’re dealt wisely. A good contender does not complain about his or her cards, but uses them in a better way. The battle proceeds, and his first Pokemon sent out is Sharpedo, the Water/Dark-type from Hoenn. I usually try to bypass it with a Thunderbolt, but sometimes, it is too fast for a couple of my Electric-types. It is faster than the average, so use a high-leveled Pokemon. Rough Skin damages Pokemon with physical attacks, so watch out for that. It uses either Earthquake or Night Slash; be careful with your slow Electric-types.
The second Pokemon is Scrafty, the Dark/Fighting-type. For some reason, I always send out Grass-types to defeat it. It uses Poison Jab or Head Smash, and is very stalwart because of its high defensive capabilities. It is weak to Fighting- and Flying-type moves.
Grimsley’s third Pokemon is Liepard, a pure Dark-type. Since it almost always uses Fake Out first, I suggest using the first turn healing your party Pokemon. Its second move is either Sucker Punch or Night Slash, giving you another turn to heal if your lead Pokemon is strong enough. Occasionally, it will use Aerial Ace for no reason; maybe for a surefire hit. Its Defense lacks, so any move with enough power can take it out instantly.
The fourth Pokemon is Drapion, the Poison/Dark-type from Sinnoh. It relies on Crunch, but has a variety of fang-based moves, like Thunder Fang or Fire Fang. Despite this, it doesn’t gain Same Type Attack Bonus, so don’t expect those moves to do much. Unlike its counterpart, Scolipede, it is weak to Ground-type moves like Earthquake.
Fifth is Krookodile, which is a Ground and Dark-type. Intimidate discourages physical attackers, because for most, that stat change is enough to break the one-hit KO. It also has Foul Play, a move which increases the more physical attack the target has. For Flying-types, it has Smack Down, which grounds them, and is a super-effective hit in most cases. I would suggest a Special attack from a speedy Pokemon.
Finally, his last Pokemon is Bisharp, which is a Dark and Steel-type. That means it has a double weakness to any Fighting-type move. Its speed is average and it relies on Night Slash or X-Scissor; it shouldn’t be too hard to take out with a physical Fighting-type move or a Special move of any other element. When you win, he says that in battle, there are good ways to lose and bad ways to win – but it’s hard to distinguish which is which. That’s a confusing statement, but it provides an insight into battling strategically. Once you exit via the portal, the northwest tile will light up, and you can proceed to fight another Elite Four member if necessary.