he main basis of classification of phylum Protozoa is:

Concept-
-The five-kingdom system proposed by R.H. Whittaker.
-The kingdom defined by him was named- Monera, Protista, Fungi, Plantae, Animalia.
-Protozoa come under Kingdom Protista.
-Protozoa is 3rd largest phylum.
-Protozoa include unicellular eukaryotes. 
-They believed to be primitive relatives of animals.
-They are heterotrophs.
-They live as predators or parasites.
Explanation-
-Protozoa are divided into 4 classes.
-The basis of classification is locomotory organs.
-The 4 classes are-
-1. Flagellata  2. Rhizopoda  3. Ciliata  4. Sporozoa.
These are divided on the basis of locomotory organs

🔴Additional Information:
-Sporozoa
-Sporozoa are all endoparasites.
-In Sporozoa locomotory organs are absent.
-They reproduce asexually by multiple fission and sexually by syngamy.
-Eg of Sporozoa is Plasmodium, Babesia, etc. 
-Flagellata
-They are free-living or parasitic.
-In this locomotion by thread-like flagella.
-Reproduce by binary fission.
-Eg are Euglena, Giardia intestinalis, etc.
-Sarcodina
-They are free-living or parasitic.
-Locomotion by pseudopodia.
-They reproduce by binary fission.
-Eg is Entamoeba histolytica, etc.
-Ciliata
-They are free-living or parasitic.
-Locomotion by cilia.
-They reproduce by binary fission and conjugation.
-Eg is Paramoecium, etc.