OK, I can see how RAW could be interpreted either way. Since the PHB section I mentioned refers to large creatures I can see how it could be argued not to apply to bugbears. My logic was not this so much as the connection I saw between the two weapon types. In this PHB section after the weapons are defined (cannot recall the page right now) I noticed that, even though speaking of what large creatures could do, it said that such a creature could use either a larger version of a medium creature's weapon or just as easily use a two-handed version of a medium creature's weapon. The section does not mention medium creatures specifically, it is general because a huge creature could use a two-handed version of a large creature's weapon, and so on, but I am just looking at the rule for large creatures at the moment. So with this said, since the PHB seems to equate a larger version of a medium weapon with a two-handed version of a medium weapon, I went with the line of logic that if a bugbear can also wield a larger version of a medium weapon then it would follow he could also wield a two-handed version of a medium weapon as well, and I mean wield in one hand of course. This based on the PHB description that seems to equate these two types of weapons when describing what larger creatures can do.
Yes, I know bugbears are not large, but I am not using that part of it, just the fact that this section seems to make the two weapon types equal when it comes to wielding them. So it did not seem like much of a jump to then assume a bugbear could wield either a larger version of a medium weapon (which is RAW by definition) or, based on the PHB section, a weapon that would be equivalent to such for purposes of what can be used, which would be a two-handed weapon for medium creatures.
So I know that would not be RAW explicitly, but it seems it could be RAW implicitly, since the RAW seem to equate these two types of weapons in the description pertaining to oversized weapon use.
Larry