Is Tekken 5 an exclusive to the PS2 or not? How does the existence of Tekken GBA make Tekken 5 no longer an exclusive? 

I remember Sony and some devs crediting PS4 for the revival of Japanese devs.

These are all shovelware titles, Sony probably let them go because they didnt want to be known as the only source of these titles.

Honestly, it means nothing at this point. Sony lost a lot of former Playstation exclusives during the 6th generation and it turned out to be their greatest generation. Sony lost even more former PlayStation exclusives with the PS3. Exclusives are definitely important, but if a game ported to a competing platform after 2 or 3 years, then it has already served its purpose by that point.

There seems to be a lot of twisting the term exclusive , let's look at Grandia it was on both saturn then PS1 followed by grandia 2 on Dreamcast later ported to  PS2 and to Windows in NA now that one is interesting since it was area  exclusive  then Grandia 3  published by Square - Enix on PS2 plus a bunch of spin offs ,so it is easy to see that Grandia after the dreamcast struggles simply went where the market for jrpg's was the strongest. Now  Switch is seen as a console with a number of things that make it ripe for porting jrpg's,  one is it's strong Japanese fan base another is the  form factor and let's not forget this is a port of a 21 year old game that been around the block .so no big change at all.

Yakuza's expansion had more to do with Yakuza sales stagnating and Sega wanting to expand the series.  Publishers putting certain games on the platform they see their sales coming from doesn't mean they will stay there they eventually follow the money trail in the PS4's case its market share was the golden egg and Xbox and Wii U underperformance meant some games that would have had PS4 as the main platform followed by the others just stopped with the PS4. now there is  enough growth to once again expand and Valkyria Chronicles is symptomatic of that it started out a niche title on PS3 and sold enough to to turn it into a series the thinking at the time was Vita would be a good fit with it's lower costs offsetting a reduction from PS3's sales especially with a fair few of those at a heavy discount, now with Vita no longer being a viable option and steam sales being ok multi plat is the way to maximise the sales.

That's a fair point with those examples. I also remember another couple cases like with Insomniac developing the Ratchet series as well as Resistance and those are 100% rock solid exclusives because Sony owns both IPs. However, that doesn't diminish my point. There are some cases such as those but if you see that the developer is owned by the console manufacturer then you have a certainty that the game will remain a rock-solid exclusive.

Grandia still was only exclusive to PS if you’re only looking at the first one and only looking at the west. The remaster is not an exclusive to any platform.

Yakuza being exclusive in the west does not invalidate what I said. It cannot be considered and exclusive if it’s on another platform.

That's true, but the fanbase is there because the games used to be exclusive. If they are multiplats and new titles are too, then with time people will consider other consoles.

Well No Man's Sky is plain shovelware. Crash and Hellblade are pretty bad, both below 85 Metacritic. Firewatch was mediocre and Edith was decent, but super short and pretty light on gameplay. So I suppose I overstated it by calling them all shovelware, but they're mediocre titles

The Sony exclusives make a difference.