'Ouma said he's enjoying being bullied (to Monokuma in Chapter 2)- that's all just a part of his mastermind plan, so it makes no sense at all that he'd complain about bullying in Chapter 4's trial.'
Well. First thing is first: he lies, rather often, so using words out of context to 'prove' he 'wants bullying all the time' is just... backwards. Especially since he's sarcastic at times- and what's more, he is so in that same scene, when he turns around to be like 'oh did you hear that? I'm just talking to myself' after saying something about not cooperating in plain sight (go figure why he'd have things made that remove security cameras). And it turns out... he had said what is important to the group's survival. Of course he wants to maintain enough distance with his mask in order to put on his mastermind-y airs, but he also wants to communicate things and be taken seriously.
Second, you'll know by Chapter 5 that he does this shit as a means to an end, but this behaviour also goes hand-in-hand with the childish way he acts in other modes, too. He maintains a similar kind of neurosis, not letting people in on himself, holding back on his emotions, et cetera. Hence, why it's necessary to point out that in fact, he may have been hated even outside of the game, and that this tendency carries over into the main game. Where it becomes apparent, that from the time he announces himself as a 'liar' and 'Supreme Leader' (whatever reasons he has for doing that, that's up in the air), people have been biased against him even when he's serious. This is something we can see play out as early as the Death Road of Despair- he's visibly very upset at Kaede forcing the group over and over, but Tenko tells him he's being 'selfish'.
Also... funny expression to make when you're totally unserious, huh.
So in point of fact, there is a reasonable amount of ambiguity as to how much of 'he wants bullying(tm)' plays into his plan. Sure, he might 'use himself as a target' to change the mood - like in the dining hall in Chapter 1 - but it's reasonable to suggest he prefers when that's on his terms, and that he doesn't want it all the time. That's a fairly simple conclusion, and doesn't take away his motives either.