I have Karlach specced as a Wild Magic Barbarian in my playthrough and haven't particularly noticed any one effect coming up more frequently than any other. Though now you say it, I might have only got the teleport one once early on - I can't even remember exactly what it does. And if the Wild Magic table is the same as per 5e RAW, I don't recall having got the necrotic damage one even once. All the others feel like they've popped up reasonably frequently, and not magic infusion more than any other. I'll pay more attention going forward though!
