Just across the bridge at the start of the Lostlorn Forest is a Pokemon Breeder, who wants to get practice by facing you in battle (I don’t get it either).

Battle: Pokemon Breeder Galen (768 Poke)
Opponent: Tranquill Lv 24, Liepard Lv 24

In the middle of a hollow stump behind Galen is an Ultra Ball (handy!).  Continue past that and poke the green lump on the ground to reveal a Pokemon Ranger!

Battle: PKMN Ranger Serenity (1560 Poke, Pecha Berry)
Opponent: Trubbish Lv 26

Her Trubbish is a bit troublesome between its Stockpile and Sludge, but since she gives you a Pecha Berry afterwards you should be fine, even if you didn’t have any Antidotes left.

Due north of Serenity you encounter a large field.  Crossing it while still heading North will let you reach a man standing in front of a tree stump who talks to you about Zoroark.  When the conversation ends, he gives you the TM for Snarl.... and then turns into Zoroark as he walks away!  Snarl is a Dark equivalent to Struggle Bug, not terribly powerful but potentially a very potent way to cut a Special Attacker’s danger level down, as it always reduces Special Attack when it hits.  Unlike Struggle Bug, Snarl has significant power, so it suits different pokemon than Struggle Bug completely aside from their differing elements.

To the East of where you met Zoroark is a Net Ball you can pick up, and wandering around here is yet another Pokemon Ranger.

Battle: PKMN Ranger Forrest (1560 Poke, Cheri Berry)
Opponent: Emolga Lv 26

Forrest’s Emolga absolutely abuses Double-Team, its Static ability, and Shockwave to reach a state of near-untouchability while constantly hitting you.  Unless you have a special-offense Ground type or can take it out -very- quickly, this thing will ruin at least one member of your team, if not several members.  It also takes a long time to defeat if you don’t smack it hard right off the bat.