So far, all Level 2 "Chemicritter" monsters' combined ATK and DEF equal 2100 while the "Poly-" ones (Level 8) equal 3000. One oddity is that along with multiple Attributes and Types, each has a combination that is rare in the game, such as Aqua combined with FIRE and Beast combined with WIND.
"Chemicritter" monsters are named after a chemical substance and an animal, while "Poly-Chemicritter" monster are given names that are a combination of two creatures (eg. Hydra + Dragon). Each member of the archetype has a symbol(s) on their bodies to represent the chemical substance that they are based on, e.g. "Hydron Hawk" having the letter "H" on its chest to represent its hydrogen basis.
The Japanese name of "Chemicritters", 化合獣 Kagōjū, derives from the word 化合 "chemical compounding". The Japanese name of "Poly-Chemicritters", 進化合獣 Shinkagōjū, also contains a blend of that word and 進化 "evolution".