I'm not really sure my enemy designs are "interesting", but I'll list some things that I've done with the few I've created and been using to test things on.
Wolf - Has a high Speed stat (at least for early in the game). It's Luck stat is also fairly high. It has moderate Defense and low Magic Defense. It's weak to Fire, and in particular the State of "Burn". They come in packs of 2-4, depending on where you're at in the game. Sometimes they're also trained and have a "Master" alongside them that usually adds buffs to them. We'll focus on the basic Wolf troop for now. It has three skills. Bite, which is a flavored version of the "Basic Attack" in the game, it deals Piercing Damage (which means it can hurt if your equipment isn't the proper kind). It has "Swift Blows" which is an ability that takes the Speed stat, subtracts your Luck stat from it, and does damage based on that (and with its high Speed stat... this can and frequently is deadly early on in the game to new players). The third skill is "Escape". Escape only activates if you manage to inflict the state "Burn" on the Wolf. Once inflicted with "Burn", it does "Escape" 100% of the time (if it survived to escape anyway) and runs away from combat.
The point of this enemy is to teach my players about Equipment. It serves as a "benchmark" for whether or not a player is paying attention to NPC's and the Armor Tutorial. In short, the enemy serves as a "Test". NPC's in town tell players that Wolves are very fast and they'll need to not wear lightweight armor if they hope to keep up with them. This is a hint telling the player to buy some Leather Armor to increase their "Luck" stat (It's renamed Reflex in my game... it makes sense, shut up

). If you're wearing that, the Wolves do negligible damage to you using "Swift Blows". Another NPC tells you that the bites of wolves really hurt and that he wished he had put on something to keep those teeth from Piercing his arm. This is another hint that tells the player that maybe they could equip Chainmail armor as a "middle ground" type armor to prevent Piercing damage from wolves (this armor, in fact, zeroes out all Piercing damage, it is full resistance to that single type of damage), but it doesn't protect as much as Leather Armor from the Swift Blows skill (damage is mitigated by about half from default stats instead of three quarters). The final NPC tells you, as you take a quest to clear out a Den of Wolves, that if you find yourself in a pinch, don't hesitate to run away... or, if you can't run away, to throw fire at the wolves because they are afraid of it.
---
Life Weaver - It doesn't do anything at all in battle except use a zero MP healing skill that restores all health instantly to the target (it can target itself, or allies). It is partnered with:
Dread Knight - This is an enemy with moderate Defense and very high attack power. It's got two skills. It has a skill that increases its critical hit chance by 50% for 3 turns (called "Spot Weakness")... And a skill that does very high damage to the entire party dealing both Physical and Slashing damage (called "Brutal Swing"). It's Speed and Luck stats are very low, so those can be exploited for large amounts of damage. It also wears Heavy Armor so you can use Blunt Weaponry or any form of Magic against it to decent effect. However! The Dread Knight is only encountered in a team of two Life Weavers and two Dread Knights.
This battle is again, intended to be a test for my players. A lesson, if you will. Before these enemies, players are given the ability to cause "Stun" to enemies. Stun, can be pretty powerful. But, it depends on how you use it. Stun works by essentially keeping the enemy from moving... ever. It doesn't wear off. Except... If you land a blow on the enemy. Any damage it takes, and Stun wears off instantly. The intended method of use for this State is to use it on "problem" enemies so you can approach combat in the most comfortable way for you. There are several options for its use in these combats. You can stun both of the Life Weavers and prevent them from healing any damage to the party and then focus entirely on the Dread Knights... Or you can Stun the Dread Knights and focus down the Life Weavers. Or, you can Stun everyone and focus down each enemy in turn, so you only have to deal with a single enemy at a time. And, finally, if you're just strong enough, you can just smoke these enemies without relying on Stun at all. Though, I don't anticipate that.
---
Pouncer - This is an early boss creature that tests you on your knowledge of the "Poison" state. It's a plant that can cast two different forms of Poison. It casts Level 1 Poison and Level 2 Poison. Sometimes it casts these as a single skill ("Foul Bile") or as individual skills ("Poison Cloud" for Poison Level 1 and "Stinger" for Poison Level 2). It also has a basic attack that hits all enemies for moderate/minor damage (called "Tentacle Sweep"). From a merchant, you can find rings that nullify Poison Level 1... or Poison level 2. But, not both. In the Dungeon where this creature resides as the boss monster, you can find "Poison Resistance Relic" which drops your chances of being inflicted with any poison down to 50%... But, it makes you more susceptible to Sleep (Levels 1 through 4) by 50% more. The same merchant also tells you to stock up on Antidotes, since they cure all poisons of any severity. Level 1 Poison deals 2% damage to you each turn. At early levels when your stats are low, this is only a single HP a turn (engine seems to round this up). Level 2 Poison does 5% damage to you each turn. At early levels, with low stats (again!), this is usually 2 damage a turn. But, when the enemy inflicts these on you, they don't wear off for several turns. You can also be inflicted with both at a time. Maybe 1 or 2 damage a turn doesn't seem like a whole lot. But, when you've only got 30 HP or so, and most enemies at that point take off 2-4 HP a hit... It's decision time. Furthermore, Poison 1 lasts 3-5 turns and cures on its own. Poison 2 lasts 5 to 8 turns before being cured on its own.
So, the player is meant to learn about how Poison works, why it's deadly, and ways to perhaps mitigate it (in the dungeon, before this boss. Most enemies in the area inflict you with one of the two types of poisons). It's also meant to teach the player about Choice in the game. The boss itself is really only difficult due to the small amount of stats a player will be working with at that point in the game (including the HP pool). You can choose to mitigate the Poison 2 stuff with that ring and just deal with Poison 1 for 3 to 5 turns if you want. You can choose to mitigate the Poison 1 stuff with the other ring and deal with the less frequently casted Poison 2 with Antidotes. Or, maybe you also equip that Relic that drops the remaining Poison chances down by half to save resources.
---
Anyway, that's really all I have for Enemies at the moment. I'm too busy making skills for my 9 characters to work on anything except a few basic enemies to test my skills on. So that's basically all I've got right now. I've got regular basic enemies, but they're nothing to write home about. They exist merely to teach the player about their stats and nothing more.