Sometimes when TCPs spawn, they can spawn as a hybrid of multiple types; but more often, hybrid TCPs are created in laboratories using a special procedure. These TCPs share the physical characteristics of both of their source types. Hybrid TCPs of 2 types are usually okay, but hybrids of 3 to 5 types are often more unstable, prone to irregular body shapes, extraneous limbs, and odd patches of different skin, as well as mixed fluid types. These effects can lead to health issues, especially if two of the types conflict or interact badly. For example, a gasoline/fire type TCP wouldn't exactly last very long. Hybrids of more than 5 types have never been observed in the wild, and attempts to create them in laboratory settings have resulted in explosions and puddles of fluid.

Hybrid TCPs also have abilities that are a combination of the abilities of the original two types, and this is where most of the instabilities occur. With the exception of very specific type combinations, hybrid type abilities tend to be very chaotic and unpredictable, often to the point where even the TCP itself isn't sure what it does.

Hybridization is not a reliable process, and two different hybrid TCPs based on the same two types may have different appearances and abilities- one forest/fairy type TCP may look and act different from another forest/fairy type, for instance. Artificial hybridization requires two or more source TCPs, and if one or more of the TCPs is unprepared for the procedure, mental trauma may occur in the hybrid as a result of the forced personality merging. Natural hybridization does not have this problem, as hybrid TCPs that spawn as opposed to being created will only have one personality to begin with.