Custom mob barely spawning

[split pollen]

I have a custom mob ready to add, but even setting the spawn weight to 500 just to see if it spawns isn't really producing anything. I'm seeing more vanilla mobs than my custom mob.

Any tips on using spawn rules effectively?

[abstract lance]

If you have more than two custom mobs using the same spawn population control, the third mob using it will spawn very rarely or not spawn at all.

[split pollen]

How would I get around that as I intend to add multiple mobs with my add-on?

[abstract lance]

There are tons of ways. You can use a different population control for each two mobs until it runs out. Then, you can also use already spawned entities to spawn your entity.

[split pollen]

How would I go about using already spawned entities

[abstract lance]

Check for if the spawned entity already has the tag, then spawn your entity and add the tag.

[split pollen]

Could you give a brief example please. I'm having trouble understanding lol

[abstract lance]

execute as @e[type=cat,tag=!spawned] at @s run summon wolf
execute as @e[type=cat,tag=!spawned] at @s run tag @s add spawned

You can put this in a function file and run it every tick. For example, this'll make every cat in the world spawn a wolf too.

[split pollen]

I understand now. I'll probably go the scripting way for more control