If the company meet up is like a retreat/reward type of meet up then it is probably tourism. For example taking the top sales executives skiing as a reward for beating targets. You would just need confirmation of the reason for the trip and what the company is paying for, this would be from your employer, probably on the same letter you would have confirming the travellers employment.
If it is like a conference/meeting but being held at a function room in a hotel or similar it would probably be business. You would have a letter from your employer confirming your employment and another letter from whoever is organising the event (can be the same company you work for outside of the schengen area) outlining the details of the trip. Along with some kind of proof that the facilities have been booked for this event. A letter from the hotel/facility for example. This way there is some confirmation from within the country you are applying to that this is a genuine business event.
I have done this several times for groups of travellers and it is fine. Interestingly when doing this the second way I mentioned, some consulates when presented with identical documents issued visas endorsed as business and others tourism. This was highlighted to the consulates in question and the response was that it was OK because it was possible to do either activity on the visas issued, ultimately what was printed on the visa was the consulates discretion/interpretation of the code.