Biletoad lists 15 pets with the same attacks, but leaves out horny toad.
Horny Toad lists 15 pets including biletoad, but leaves out lifelike toad.
Lifelike Toad leaves out horny toad.
It looks like all 17 of that group list 15 alternatives, and I can not see a pattern as to which frog/toad is omitted.
Desert spider has 12 replacements, including Amethist spiderling, which only has 10 (desert spider and venomspitter hatchling aren't listed)