To wrap up this question… no, Wizards Unite classes are not similar to Pokemon GO teams.
In Pokemon GO teams compete against each other and you can only benefit from bonuses / gyms players from your own team.
In Wizards Unite, all players are on the same “team” and classes (aka Professions) allow them to play different roles. Having different classes in Fortresses is essential, similar to regular MMOs where you need a healer, a tank and a DPS.
Moreover, you can (and should) switch between Professions actively to fill out whatever the need of your group currently is.
No, the professions seem to be modeled on an MMO Trinity style system. So for a team of 3 you’ll probably want one of each.
I’m thinking Auror is your direct damage dealer, and maybe shield VS other players.
Professor is probably the support character, healing, buffing/debuffing, potions etc.
Magi is probably a pet handler class, maybe able to tank via pet, and possibly CC.
Each class will have its own strengths, and weaknesses that can be filled by the other classes. That way you force people to not only play together, but also to play different classes/professions.
Those are my guesses until we get some decent beta leaks, or early access for preregistration.