What is onboarding/training with the team at the start of the internship like? Regarding excel modeling, powerpoint, etc

When you start at Roland Berger, you will have a two day kick-off in our Munich office. You will get to meet all of the other interns of your intake and will get basic training on the core skills that a good consultant needs (Excel, powerpoint but also presentation and other soft skills). A lot of the "real" training then also happens on the job - Our consultant will invest time and effort to get you up to speed quickly and teach you the most valuable "tips and tricks"

Got it, so for interns with roles outside of Munich, e.g. Berlin, there would be this 2-day kickoff in Munich and then they head over to the other office base for the remainder of their tenure?

In general yes but in detail it depends on the project and the project requirements the intern is staffed on. For instance some projects travel to the client site or meet in different RB offices for their work.