Riolu
Base Stats: 40 HP / 70 Atk / 40 Def / 35 SpA / 40 SpD / 60 Spe
Abilities: Steadfast / Inner Focus /
Prankster
Riolu is an unique offensive threat. It has a good Attack stat and solid speed, but what defines it as a successful offensive threat is access to both Copycat, usually considered as a gimmick move, and Prankster, so Riolu has an incredible niche as a revenge killer. Copycat combined with Prankster allows Riolu to use an opponent's move with priority. It can use its own moves with priority too; it just need to be the last move used in a turn. Drain Punch provides a very reliable way to Riolu heals its HP back and do solid damage. Protect with Copycat allows Riolu to copy the opponent's last move with safe. Swords Dance boosts Riolu's Attack to sky-high levels. High Jump Kick is an even more powerful move, though less reliable. Even Ghost-types, such as Pumpkaboo aren't safe against Riolu; it has access to Crunch, and while Pumpkaboo is faster than Riolu, the Copycat + Prankster combination makes it be worth nothing when Misdreavus switch into Riolu. Substitute is another indirectely offensive move that allows Riolu to avoid, for instance, Misdreavus's Will-O-Wisp and then Copycat it.
Grimer
Base Stats: 80 HP / 80 Atk / 50 Def / 40 SpA / 50 SpD / 25 Spe
Abilities: Stench / Sticky Hold / Poison Touch
Grimer is quite the underrated Pokemon, but it's an incredible defensive threat. Its 80/50/50 defenses are incredible, and with Sticky Hold, this guy is one of the best counters to Mienfoo and Pawniard. Dealing with Mienfoo is easy because of that Fighting-type resist, and while Pawniard still has the 50% from Knock Off, Grimer can deal with it with its Fire Punch and very high Attack stat. Sticky Hold allows Grimer to always keep its Eviolite so it can act as a Knock Off absorber. Curse allows it to become even more bulky, while still keeping an offensive pressure. Pain Slip can also be used for recovery.