Celery x Univolt for petalia
Petalia x Mossanda for Lyleen
Lyleen x Menasting for Lyleen Noct
Menasting is the biggest issue, it's not much weaker than Lyleen noct in the wild

If you want to get A rather... Interesting Lyleen, I can tell you how to get the Boss Lyleen with Lily (Its A Glitch, So it may get patched out at some point but do this for the chance of getting one!)
Step 1 - Find the tower Lily and Lyleen are in, Its in the Small Icy area thats not apart of the Big Icy Mountain, Make sure to wear the Tundra Clothes
Step 2 - Unlock the Fast Travel in front of the Tower
Step 3 - Go to the Small Settlement and, If you have A Bow, Crossbow or Gun, Shoot the Guard and get A Wanted Level
Step 4 - Go BACK to the Lily & Lyleen Tower once you get the Wanted level and go into the Tower. Skip the Cutscene unless you wanna watch it fully
Step 5 - Do not Attack the Lyleen, Dodge ITS Attacks as PIDF will appear in the tower with you, Let them hit the Boss instead
Step 6 - Once the Boss has been hit, They'll go towards the edge of the Area, Throw ANY Pal Sphere and, Regardless of what it says, you will 100% capture the Lily & Lyleen Boss
Step 7 - Go to your Options and do RESPAWN, and go back to your Base
Step 8 - Go into your Palbox, Find the Lily & Lyleen and place them into either your Party or into the Work area and Enjoy having an Actual Boss Pal with their Human Partner in Palworld

These steps also work for the other 4 Bosses as well

I like that they are subspecies, its quite a nice feature that species can change depending on their environment, and through breeding ect.

They look so wonderful together in this image!

Lovely look.