Cassette Beasts is a monster catching RPG that looks like another pokemon clone at a first glance, but it's so much more of a different experience and I believe stands very unique among its' genre.
I adore how this game handles its type chart. Instead of certain types doing more or less damage to each other, in this game, type advantages and disadvantages are communicated through status effects. For example, a water move against a fire type won't do any extra damage; however, it will "extinguish" the fire type, lowering all it's offensive stats.
An air move against an electric type won't do less damage, instead it will make the electric type conductive, letting them hit multiple targets on the field for a couple of turns.
A Poison move won't automatically fail against a metal type, instead; the metal type will "use the additional poison leftover from the attack to coat its blades", giving the metal type poison-type contact damage for a couple turns, letting it return a little bit of the physical damage it takes and doing a little extra poison damage with it's physical attacks.
Fire moves will "steam" water types, giving the hit water types passive HP recovery every turn for a couple turns, etc.
I think it's a really unique approach to a type based system that, instead of centralizing it's entire win condition on type matchups, it lets most beasts fight on even ground, with slight yet impactful advantages they can gain for themselves by playing smart.
Battles in this game are also in a 2v2 setting. You can have 6 beasts on your team but you will always fight battles two on two, with the rest of your team you can switch into at will.
Another interesting part of this game is that the beasts you collect aren't really creatures fighting by you side. Instead, you "record" the creatures to add them to your roster, and then turn yourself into them. Mechanically, this isn't much different at all from just having multiple pokemon in your party in a game like pokemon. The difference comes from the fact that, as you are turning into these creatures, both the beasts and you have separate health bars you have to take into account. This also goes for every "trainer" type battle you will encounter of course. Your beast's health hits 0, it gets KO'd, you switch into another one, no big deal. YOUR health hits 0, and it's over.
If one of your beasts gets KO'd, the leftover damage it took spills over to your actual player character, and taking enough damage as your player avatar means you're out of that fight for good, and must let your partner fight a 1v2. Having one of your beasts be KO'd also means you are vulnerable and in your human form for the rest of that turn, so any attacks that had targeted you that turn are now very dangerous and can potentially take you out of the fight for good.
You can also of course use this to your advantage to beat down the Captains (gym leaders, essentially) or other trainers quick enough that they lose before they get the chance to switch into their stronger beasts in the back of their team.
This all introduces an extra layer of strategy to switching out or staying in. If you're wounded and know a strong attack is about to hit you that you can't avoid, do you switch to one of your healthy beasts and let them take the blunt of the damage, crippling them for the rest of the fight, or do you stay in, get KO'd, take heavy damage to your player avatar, but get to switch in a healthy beast for the upcoming turn? It's very good at making you think on your feet, and the double battles let you set up some wacky strategies with your partner.
The game also has incredibly good music, would be a crime not to mention that.
If I had one complaint for this game, it would be the movement. It's simply not fun to move around. Getting stuck in tiles while dashing happens far too often and the stamina management in early game feels really annoying and doesn't mesh well with the genre. Most of the annoyances of overworld movement gets better as more upgrades are unlocked, but it always feels slightly clunky. Not bad enough to deduct a point but certainly a little annoying