well, he was the hoenn champion. he gave the role up to wallace in emerald, though. whether he'll still be the champ this time around is ambiguous imo. there's certainly precedent for including third-game elements in paired-game remakes, with HGSS. i do hope wallace is the champ this time around, since it'd make mega milotic more likely.It might be me forgetting, but was Steven's role in R/S/E explicitly mentioned? If not, this is a cool way to take advantage of that ambiguity left from the older games.
aside from that, he's the son of the devon corp owner. so he's basically the heir to hoenn's version of silph co. and steven in particular studies rare stones - he's involved with evolution stones (like fire/leaf/etc) as well as fossils.
also, he gives you a beldum! what a nice guy. (please include metagrossite this time steven thx)