Companions are pets that will follow you and attack any hybrid you try to kill. As of the new Pet Update, there is a GUI you open by clicking your companion's name on the top left corner, near the mutant market.These Companions can be useful for protection on PvP servers.
You can obtain a free companion in the tent of Shooba, a merchant of Yandi.
You can also get a Pet by using an Egg Fuser.
You can also obtain a free companion in the cyan castle of Shindo, at the right once you enter it.
Attack Something - Attacks at what you tap.
Walk Somewhere - Goes where you tap.
Hold/Use Items - So far your Companion can only use and equip armor and weapons. Total storage 9 items + 3 wearables.
Wait Here - Your Companion gets placed where you tap. NOTE: Companions can get deleted and/or lost if you delete where they're currently waiting in (e.g. beanstalk, house, tent, etc.).
Rename - If you're not happy with the name you gave your Companion upon being hatched, you can rename them for 2 Gems.
Leveling up & Item usage
Unfortunately, your Companion will not be balanced to the level you have, and cannot be leveled up with Bone juice. The developer of Hybrid Animals, TheFirstHybrid, has mentioned that he plans to add a feature that would allow for you to feed your Pets various consumables including the ever popular Bone Juice.
Companions may also level up by gaining XP, which can be accomplished by allowing them to kill enemies.
Your Companions' attack and protection can be increased with armor and weapons. Armors' special ability works, but it is unknown if any of the swords' does.
Unfair leveling up
Many of the Companions' features are still in development. This means that there are going to be a lot of unfair ways of progression
If your Companion is at a very low health, you can put them on wait and un-wait to restore them to full health. This can be used to survive and kill high XP enemies and bosses to level your Companion up very quickly... or you can kill-steal from your Companion for yourself.
Open the Companion menu while they're attacking an enemy and close the menu to achieve insta-attack rates. This is useful for all of you impatient people, but note that the enemy attacks are also instant.
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Companions have been in the game since 2019 and had very devastating glitches before. It would be stuck in a certain level unable to be leveled up. This has been fixed now.
In rare cases in which a player's game did not write save information properly, "waiting" Companions that had been placed on a Personal World would corrupt and would lose all their levels, inventory items, and levels. This bug has since been researched and worked on by the developer in an effort to remove the break.
Another situation pertaining to save writing going awry is the "Data Unavailable" error. This error occurs when a Companion is placed on a Multiplayer server and the game fails to properly write into the "waiting" companions save file. This error will then appear upon attempting to get the Companion to follow you, rendering the Companion unobtainable.
Other Features and stuff to come
In the future, you will be able to turn companions to merchants (similar to the current NPC merchants) and mount (ride) them.
There is also confirmation of a new "Behavior" feature coming in a future update, which will likely allow the player to determine how their Companion(s) shall behave (eg. attack unknown players that approach their owner or a certain location).
Companions will be receiving their own independent Skills and Powers in a future update as shown by the gray "coming soon" button on the second page of the Pet GUI.
Also as of the new 2020 Update, companions can carry armor, swords, and items! As of another update, companions can no longer equip the best armor without being a high level. Be careful if your companion is a low level. Try sending them to attack colorful XP Orbs so that they level up.