Here's a non-finished tier list for the Creature battling.. if the event stays as a permanent event, this will be reworked into a guide.. enjoy fellow gamers!
(" Ctrl + F " can help you search for the creature you want)
ULTRA RARE
Gravitonic bork pet (BST: 618)
Frost dragon pet (BST: 612)
Adsz's pet (BST: 580)
Philosophous hydra pet (BST: 572)
Storm pet (BST: 571)
Wisdom dragon pet (BST: 569)
Pet olmlet (BST: 565)
Guardian titan pet (BST: 564) *sidenote; Best tank pet*
Chasmquaker pet (orange) (BST: 562)
Solar demon pet (BST: 560)
Galvek pet (BST: 558)
TzFrozt-Jad pet (BST: 556)
Chasmquaker pet (purple) (BST: 552)
Lunar demon pet (BST: 552)
Ripper demon pet (BST: 517) *sidenote; Best burst pet*
VERY RARE
Galvanic golem pet (BST: 540)
Pet dagannoth rex (BST: 540)
Pet zilyana (BST: 539)
Baby steel dragon (BST: 537)
Superior wyvern pet (BST: 536)
Vorkath pet (BST: 536)
Vet'ion jr. (purple) (BST: 534)
Lava dragon pet (BST: 535)
Pet kraken (BST: 534)
Skilling spirit pet (BST: 532)
Nylocas vasilias (silver) pet (BST: 531)
Gladiator titan pet (BST: 531)
Superior ape pet (BST: 531)
Abi's pet (BST: 528)
Enormous mole pet (BST: 527)
Superior k'ril tsutsaroth pet (BST: 527)
Tekton pet (BST: 526)
Easter dragon pet (BST: 525)
Dharok pet (BST: 525)
Corporeal beast pet (BST: 523)
Justiciar pet (BST: 521)
Magic berserker pet (BST: 517)
Ripper demon pet (BST: 517)
Demonic tarn pet (BST: 512)
Summer gorilla pet (BST: 512)
Superior graardor pet (BST: 510)
Gargoyle (BST: 509)
Haunted spectre pet (BST: 508)
Baby iron dragon (BST: 508)
Pet dagannoth supreme (BST: 508)
Lava giant pet (BST: 506)
Pet dagannoth prime (BST: 504)
Callisto pet (BST: 500)
Raw's pet (BST: 497)
Statius's spirit pet (BST: 497)
Muttadile pet (BST: 490)
Dark beast (BST: 489)
Demonic bunny pet (BST: 486)
Prayer spirit pet (BST: 485)