Through my eyes two problems may occur due to training clans/B-Teams in same division:
1. Template voting
2. Loosing intentionally
Also have to be mentioned, that same problems can occur, if two clans/players are chummy. You can not completly prohibit such situations. Both problems are caused by the system of the league itself, but stressed by "training clans".
4. Even in the case where the "training clan" wouldn't had received help from borrowed higher skilled players belonging in the Alpha clan, would it really make sense to have a lot of training clans taking over the spots of divisions B or A?
I think "training clans" are a great idea for warlight in general. Warlight does not have that much players (esp. skilled ones) and therefore training clans help to increase the general skill-level. And if one does not want to prevent this increasement of skill by "training clans", one has to give these training clans the possability to competete in events like CL. And why not? At the moment these "training clans" do not harm the competition in CL.