What’s the difference between pets?

Following the calculation for your actual resistance, you'll see that each further point of internal resistance has less and less impact on your resulting percentage.
Here is a chart that illustrates this nicely:

A rising resistance also produces a hyperbolic growth to your effective HP, but what does this actually mean? A pet with 500 HP & 50% PR could absorb 1000 points of physical damage, so we’d say it effectively has 1000 HP. Now, imagining the same pet with 75% PR, it would have double the effective HP, despite just having a 25% increase in resistance.

eHP values aren’t the be-all and end-all, since there’s also damage that avoids resistances, but they help a ton when comparing tanks with one another. In situations where one resistance is overwhelmingly more important than the other, we typically push said resistance-stat up to 3 to optimise eHP, but for more typical tanks, 2 for each is the default choice.

We use this formula for the calculation: eHP = HP / (1 - Res)

Using the stat-system I explained above, let's have a look at Lovebunny and Slothbot:

OwO✓APP

 2023val_lovebunny

"...what are you looking at?" Art drawn by @novareid Holiday pet created on February 2023 for Valentines Day!

Nickname: bnuny
Count: 0/6
Rank: special
Rarity: 137,296 total caught
Alias: 2023val_lovebunny, lovebunny, bnuy
Points: 500
Sell: ???
Sacrifice: 5000 Essence | 6 killed

8 1 1 8 1 1 

OwO✓APP

 slothbot

Their movements may be slow, but every motion by these sloths is calculated. They climb to the top of the trees to take in the energy of the sun, preserving their strength. You won't believe their eyes when they show their power

Nickname: Pride
Count: 0/4
Rank: bot
Rarity: 37,376 total caught
Alias: slothbot, sloth
Points: 30000
Sell: ???
Sacrifice: 10000 Essence | 4 killed

9 0 2 8 0 2 

Lovebunny is a WP-tank with 20 stats and Slothbot is a WP-tank with 21 stats. We typically ignore the STR and MAG stats on these pets though, since they're useless here. Slothbot has zeroed these stats, which typically have a minimum of 1. By doing this, Slothbot is +3 stats better in the relevant ones. And by being +3 stats better than a 20stat, we consider Slothbot to be a 23stat pet.

This concept gets complex rather quickly, once you try to expand it outside of Bot Pets, because when is a stat wasted, and when is it just placed suboptimally? Should a 20stat with one mediocre stat choice be considered a 19.5stat pet? It's difficult to say, so we usually only use the concept when talking about Bots and Bot-likes.

While there are only rough and vague categories of pets.
I’ll still try to give a basic understanding of why we call pets a certain way.

# Tanks

Tanks are pets based on tons of Health and Resistances, doing as their name would suggest—tanking.

## Pure Tanks

• Pure Tanks are the most extreme of Tanks, allocating all their stats into HP, PR, and MR.
• In current meta, they’re commonly seen holding critically important weapons while being replenished with WP.

## WP Tanks

• WP Tanks are similar to Pure Tanks, with some added WP.
• On teams where you can’t count on replenishment, choosing a pet with extra WP is the only way you can ensure reliable procs of your weapons.

## Hybrid Tanks

• Hybrids—true to their name—are to some extent both Attackers & Tanks, performing multipurpose roles.
  • A Gorilla with Shield for example, keeps taunting the enemy,
    and thus protects its team, but also attacks with its Strength on off-turns.
  • A Snail with Sstaff in Pstall on the other hand, can tank quite a bit of damage and survive,
    while also using its Sstaff effectively.

# Attackers and Supporters

Attackers and Supporters are pets based mostly on Strength or Magic, as these are the stats that their weapons act upon.

## Attackers

• A pet holding a sword for example, deals damage based on it’s strength, so it makes sense to maximise this stat as much as possible. The same also applies to the magical side of pets too.
• And there’s even attackers that have both high strength and magic, such as Monkey! But these pets are usually considered quite useless, as the only weapons that can make use of such stats are Rune and Lrune, which also work with normal strength or magical attackers.

## Supporters

• An attacker can always count on massive replenishment from Mtap, and even if that doesn’t work, an attacker not acting is likely not going to end in a lost battle. But if your healer suddenly stops acting, that very quickly ends up disastrous. So in similar logic to WP tanks, supporters have some added WP to ensure their acting, giving up some power in exchange.
  • Magic-based supporters are commonly called Healers and Replenishers.
  • Strength-based supporters don’t have an established name, but are commonly seen holding buff and debuff weapons like Banner & Axe, and thus called “Banner Holder” or “Axe Holder”, depending on the situation.

Other useful terms:

• Gems are pets with near zero, or zero stats in tankiness, and are usually considered the glass cannons of the game.
• Bots are pets with zeroed strength and magic, which makes them uniquely suited to tanking. I’ve explained a little more above in Effective Stats.

Continuing from the triangle chart above, there’s some pets that don’t fit into the graph.

Crune is an incredibly unique weapon in the game, which uses the PR and MR stats for healing and replenishing respectively, thus using them effectively as “power stats” like other weapons use Str and Mag.
These stats, which are somehow power stats now, still make their pets incredibly tanky though.
And this unique situation makes it impossible to plot Crune Holders on the chart above, which neatly divides stats into “tank”, “power” and “wp”.

So I made a new chart, entirely for crune holders!

Notes:

• On a purely technical level, this one completely ignores Str and Mag in calculations.
  It would assume Capybara to be an 18stat.
• Why is the “non-shielded” area so empty?
  Because bots just mog everything else, lol.