There's no sense in any tech against Greninja aside from Tina promo. Spoons are pretty meh because they're easy to field blower, and Greninja always runs high counts of them to deal with Garb. They don't work if you attach them to a pokemon already under the effects of shadow stitching on the turn you attach them, so they're one of those tools that only does something if your opponent can't counter it on their turn.
For me it comes down to the investing to make bad matchups less bad vs making good/neutral matchups more consistent, that's always the tradeoff. Greninja is deck #8 in CP standings in the 2017-18 season, so while it might still have relevance it's pretty low on the totem pole. All of the cards used to deal with Greninja are dead cards in the other matchups you'll face. If you can't take your bad matchup to neutral in 1-3 cards it's, for me, usually not worth trying to tech for.
