I honestly kinda got complacent. I have a really bad habit of choking in sets like that in general. My thought process shifted from, "Well, I got wrecked in winners semis or whatever, so I'll just do what I can," to "Wow, just need to not mess up three times, and I got this!" I have some mindset issues to work out haha. I still think those first 5 games in GFs are probably the best I've played with Greninja, so I can be proud of that at least.
In general, I've been told I play a lot better when I don't really care. I feel like I end up putting a lot of pressure on myself at times because there are so few Greninja reps in the states, and I really don't want to let you guys down, and that kinda gets to me. It's definitely something that I need to work on.
As for better Greninja mains, well, Ace told me about a California Greninja he played that impressed him, and as mentioned, there's Ninjalink. I've recently been working on my offensive play (which explains why I played really aggressive in some of those sets) so that being behind isn't too bad an issue for me, and hopefully that's gonna end up helping out a lot. Seems now I also gotta work on my mindset, too, though haha.