Do you like punishing yourself? Well, I don't and I think that's a little weird. But, regardless, if that's your thing then BetterHardcore is the answer to the question you weren't even asking. This mod adds configurable difficulties that apply restrictions on an otherwise normal Pixelmon playing experience. Some of (but not all) the things that difficulties can restrict the player's ability to do include:

Healing (implements a cost to use healers/Nurse Joy NPCs)
Item clause (no items in or out of battle)
Nuzlocke mode (Pokemon dies = removed from party)
Species clause (can only catch one of each species per playthrough)
Use of pretty much any common item (TMs, Rare Candies, Potions, held items)

Some other things it can do:

Restrict the player's ability to use Mega Evolution, Z-Moves, and Dynamaxing, locking those gimmicks behind a permission
Attack damage modifiers (making your moves always not very effective against opponents while making their moves always super effective against you)
Disabling the STAB modifier
Catching and leveling tiers (i.e. can't catch level 50 Pokemon right off the bat, and can't over-level your Pokemon)

And so much more! There's a toggleable boss bar that displays how long you've survived. If you lose all your Pokemon (i.e. lose a battle) and "white out" or die (like Minecraft "oh shit I fell off a fucking cliff" dying) the mod will pull the first available Pokemon from your PC it finds and repopulate your party with it. If no Pokemon exist in the PC, you're brought back to the starter selection screen. Inventory can be told to clear on a death.

COMMANDS
/betterhardcore

/hardcore
/bhardcore

/betterhardcore reload:

Requires betterhardcore.command.admin permission
Reloads configuration settings, creates new difficulties if there's one to create, etc

/betterhardcore assign <player> <difficulty>:

Requires betterhardcore.command.admin permission
Assigns the specified difficulty to the specified player

/betterhardcore toggle:

Requires no permission node
Toggles the boss bar day counter on/off

DEPENDENCIES

LypakaUtils
Pixelmon

PLEASE NOTE, BETTERHARDCORE IS CURRENTLY IN ALPHA. Most things SHOULD work, but there might be a thing or two I missed here and there. Please report broken or otherwise non-functional mechanics in my development Discord, link below.

Support, suggestions, questions, updates (because I very very rarely come here to CurseForge) can all be found in my development Discord along with all my other mods I casually toss out there for the community to use. https://discord.gg/6kKcz2kWgF