<Snipped quote by Double>
You could just have him speak normal.
I've already established him using Buu speak. It would be weird to suddenly change that for no reason.
@Double have Momo absorb an English professor and gain the ability of good grammar.
Momo doesn't know about the absorption ability. At the time I figured it would keep him from just absorbing all our enemies away and becoming stupidly OP in the process.
@Double Have him run off with Wain after the Raditz arc, and they can both come back as villains.
If Wain presents a good reason for him to do so... that might actually be tempting. I take it you're not planning to use Wain for much longer either?