This is a popular genre, as there are quite a number of trainer aircraft kits available.
The IMAM Ro.41, Breda Ba.19 & Ba.25 and Caproni Ca.100 trainers are mentioned elsewhere on this site, but there are also the following to consider:

Avia FL.3. RS Models released a trio of very high quality 1/72 injection kit of this lightweight trainer. It is a delightful little kit, with fine detail and lovely crisp moulding. Italiankits have produced a nice looking 1/48th resin kit and Ali d'Italia printed a neat mini reference guide for this aircraft.

CNA PM.1. A high wing monoplane trainer aircraft designed by students of the Instituto di Construzioni Aeronautische del Regio Politecnico di Milano in 1938. Only a small number were built and none survived the war. Post war, it was revived by Macchi as the MB.308, which was fitted with a tricycle undercarriage and an enlarged tailplane. SEM Models 1/72 kit looks fine in the box with nicely cast resin pieces.

Nardi FN.305. The 'mini' Ali d'Italia reference booklet proves just how adaptable this aircraft was. It was built in a bewildering variety of shapes and sizes, not just in its training role but as a series of racing, record and single seat versions as well. The old 1/72 Legato resin kits were disappointing. Azur produced better quality 1/72 injection moulded kits and are highly recommended. Special Hobby also issued a series of fine 1/48 injection moulded kits. The LF Models 1/48 resin kits of the FN.305, FN.315 & FN.316 are interesting but do not have the same finesse as the Special Hobby counterparts. Aerofan # 97 has an in depth article on the FN.315.

SAIMAN 200. A small biplane trainer used alongside the Caproni Ca.100. Choroszy Modelbud produced a delicate 1/72 resin kit of this aircraft. JACH Models released a good quality injection moulded kit in 1/72 which has since been re-issued by AZ Models with more decal options.

SAIMAN 202. A side by side two-seat low wing monoplane trainer with an enclosed cabin. Kora Models have released a series of 1/72 injection moulded kits, all based on the same tooling, although it does come with a resin cast canopy. Subjects covered are Italian civil & military options as well as German, Hungarian and Croatian aircraft. It has also been doubled up with AZ Models Bf109 G-6 kit in Swiss, ANR and captured RAF themed boxings. The model is a typical limited-run kit, so some refinement of parts will be necessary. For example the trailing edge of the one piece solid wing in particular needs some thinning.
Italiankits intend to release a 1/48 resin kit of this aircraft in the near future.