Sun and moon was February and XY was January. If not this month, 100% before the end of the fiscal year 

Vague announcement doesn't necessarily mean anything but it more than likely means a game is very early in development, which was further implied by what has been said about these games since and how nothing has been shown yet. We also know nothing about their budget or time demands, but it's as simple as looking back to the Prime Trilogy and the two Bayonetta games we've had so far to see that these are supposed to be high-profile releases that do require a good amount of time and money to make, there is no reason why Prime 4 and Bayonetta 3 wouldn't follow suit and in fact nothing so far has indicated they wouldn't.

In fact, I suggest you go back to Nintendo's 2017 E3 presentation and watch the Prime 4 announcement. Yes, they say "now in development for Nintendo Switch", which does imply it's early in development (never mind Reggie later stating they purposefully showed the game earlier than usual to appease fans), but what I really want you to take note of is what comes right after it. It was a new game announcement with plenty of gameplay going on and all - that game was Yoshi's Crafted World, which is only set to release this year. I don't think the Yoshi game with loads of gameplay shown and the "logo and a 4" trailer were just a few months apart.

You are right about S/M.

But look at the trend, if there is a Pokemon game the previous holiday than they go with a May/June reveal. If they dont have a Pokemon game in the previous holiday they reveal in Jan/Feb.

Holiday 2018 had a Pokemon game so a May/June reveal is more likely.

Not sure, they revealed XY literally the second week of january(the 8th) while BW2 was still selling 

Wait did they announce them or "reveal" them? Also did they come with directs or videos? 

Cause I wouldn't be surprised if they just like released the title or logo but I don't see much else. 

Yeah, X and Y were revealed during a Pokemon Direct in January. They showed actual gameplay footage, the starters, and the legendary Pokemon.

You might be thinking of Sun and Moon, which were announced in February but not revealed until May.