There are stages or tiers for Demonic Beasts.

Fledgling Tier 1

Fledgling Tier 2

Fledgling Tier 3

Adolescent Tier 4

Adolescent Tier 5

Adolescent Tier 6

Adult Tier 7

Adult Tier 8

Adult Tier 9

King Tier 10

Legend Tier 11

Demon General Tier 12

Demon Lord Tier 13

Demon King Tier 14

Demon Emperor Tier 15

Now the comparisons these tiers have with a mage's stages are as follows:

For each tier from Fledgling Tier 1 to Demon General Tier 12, they are equivalent to three of the stages. So, Fledgling Tier 1 is on par to Novice 3rd Stage, Fledgling Tier 2 to Apprentice 1st Stage, so on to Demon General Tier 12 on par to (Element Name) Apprentice.

Then, Demon Lord Tier 13 is on par with (Element Name) Grand Magus.

Demon King Tier 14 is on par with (Element Name) Grand Meister.

Demon Emperor Tier 15 is on par with (Element Name) God.

Thus, there are no recorded demonic beast with strength on par with a (Element Name) Highgod.