I think it's safe to assume that we know too little about new mons to speculate how well they'll perform both in-game and competitive-wise. Not only we know them superficially, but we don't even know if Su/Mo will introduce significant changes that could radically transform their potential. Alolan Raichu isn't an exception: do we know if its typing will have the same set of weaknesses, resistances and effectiveness? While it's likely, we really don't. Do we know if terrains will be easier to set in 7th gen? Partly yes, because of Electric Surge, but we don't know how many setters we'll have except Tapu Koko, we don't even know if there'll be an item to prolong terrain effects. Do we know A-Raichu's movepool? It could be similar to today's Raichu, but it could also be radically different: it could be better or worse, it could have better coverage, new powerful STABs or overall useful moves, or it could get nothing of it. Do we know if it'll has other abilities? It could easily have at least an hidden one. The games could be filled with pokémon weak to electric and/or psychic attacks, or the competitive scene could see the arise of new threats weak to this combo. We don't even know its stats, except for HP and maybe speed (base 110 at least I think, it's faster than Gengar in the trailer... We don't know anything about their IVs/EVs, but it's pretty safe to assume that it will maintain its original base speed stat, or get a little buff), what if it gets something like base 150 on one offense? Not that I find it likely, but it's hard to predict anyway. All this just to say: I know that speculating is fun, but getting into harsh discussions about it it's quite pointless.