I suggest just having stats, instead of templates, for "generic" infested terrans, like the explosive original type, Starcraft IIs infested marines, infested colonists and aberration, etc. However they might have additional mutations as well, with many of the mutations from d20 Future being appropriate. Then their would be a template for exceptional infested. In game the infested tend to be somewhat uniform, but other material shows that the effects of the virus vary, including its effects on intelligence. The aberration is the most obvious example of extreme mutation in infested lifeforms. There are also varying strains of the virus, which result in different attributes, such as the UV sensitivity of the infested on Meinhoff. There also appear to be other forms of infestation, with Infested Kerrigan having emerged from a chrysalis, Stukov being resurrected by infestation and subject to genetic engineering by Xel'Naga and experiments by both Zerg and Terrans. Zerg strains in general tend to have varying mutations and variations. Buildings, of course can also be infested and it has recently been revealed that vehicles can be infested.