Boss pets have been fully added to Cryptic-RS! You can obtain them by killing their corresponding boss, or by donating for them for $10 Each. The Boss pets are located below.
Corporeal Beast Chaos Elemental Commander Zilyana General Graardor K'ril Tsutsaroth
Kree'arra Ganodermic Beast King Black Dragon Nomad Nex
Theres also 2 more in-game that are not a drop yet, but are still available for donation.
Lava Monster Lava Brawler