@Angelo Any suggestions?

Thanks for tagging Anna,

Bonjour,

from Lousanne there are some direct Eurocity trains to Milan. Reservation needed 11€ in 2nd class or 13€ in 1st class. You can buy the reservation at CFF ticket office or online at Austrian ÖBB tickets.oebb.at - one way ticket - discount code: Interrail/Eurail Global Pass. 

From Milan there is a regional express to Genova (Genes) - no reservation. From Genova there are Frecciargento train to Florence, but I would reccomend to take regional express (RV - regionale veloce) because so you can stop at one of the beautyfull Cinque Terre Towns where you can get only with trains. From there you can take with changes trains to Florence and Pisa. Florence to Rome there are Frecciarossa High Speed trains to Rome (10€ reservation, same here you can get it via CFF ticket office or ÖBB online) or also slower Intercity (3€) or much slower Regional Express (RV) for free. 

Same from Rome to Neaples you can take Frecciarossa, IC or RV. 

From Neaples there are direct Frecciarossa to Venice (10€), booking works like before via CFF or ÖBB.

From Venice there is one time per day a direct Eurocity to Geneve via Lousanne. (11€ or 13€) via CFF or ÖBB. 

You can book all train also via interrail.eu but I don't reccomend it, because there are some problems and because you pay 2€ more.

You can plan your trip with cff app or cff.ch and double check it with trenitalia.com and also in the Railplanner app bit this app is not uptodate most of the time

A GLOBal pass is likely to cost more as 1 country ITalia-and pay extra (but all swiss have some kid of HalbTax or gleis&) to Domodossola=border point.