The vast majority of throws use c sized bearings, old spyy and hspin use d sized bearings, some yoyojam loopers and offstrings use size b, and some duncans use a sized bearings.
C bearings are “large” bearings, a sized are “small” bearings. Really though, just check out the stats on the yoyo’s page. It’ll tell you.
There’s a bunch of other sizes. What uses what is too numerous to list on the forum. I am compiling a database with this stuff on it. The vast majority are C-bearings. A’s are a second. D’s are a third, but distant.