It's only appropriate for Dark Souls 3, a game that asks you to be your very best (like no one ever was) to eventually receive a Pokémon mod in which to catch monsters becomes your real test, predicated, of course, on the desire to train them (the cause).
The Pocket Souls mod is an impressive Dark Souls 3 Pokémon overhaul that adds new weapons, armor, items, boss battles, and, of course, the ability to capture monsters, befriend them, and deploy them against others. Most importantly, you get a little Pokémon trainer backpack.
I haven't had time to poke around the mod too much, but it's pretty well thought out, both a cute ode to the Pokémon Gameboy games and a legitimate way to play through Dark Souls 3 for the umpteenth time.
Every starting class is now accompanied by a starter monster to get things rolling, but then you move through the game as usual. The catch is you can't use weapons and have to rely entirely on your monsters to get you through Dark Souls 3.
And just like Pokémon, you'll need to fill out a party by beating down monsters into an inch of their life before capturing them in a Pokeball, or an Abyssal Flask, a much more honest name if you ask me. There are Great and Ultra variants for tougher monsters, of course. Tossing a flask gives a cute little readout based on whether you succeed, fail, or miss the monster entirely.
Captured monsters are sent to your PC, just like in the game, which is the spell attunement menu accessible at bonfires. Here you can select your party from captured monsters, and what buds you bring along actually matter. Check out the gameplay video up top to see what I mean. Some tough battles with Lothric and Outrider Knights require a full party, and these melee-focused opponents go down pretty easy to carefully deployed ranged monsters.
There's no need to toss out your early-game monsters either. Like I used to carry Bulbasaur with me from my first bout with Gary to the Elite four, you can take a hound-rat from Iudex Gundyr to Slave Knight Gael by using Pocket Souls' leveling system. You can "sacrifice" essence gained from battles to Professor Curserot and level up your little dudes, so go ahead, let the love in and make those lasting bonds. Be the very best.