I started a new save using 15.3 with Viitorul Constanta and tested for an entire season. In fact I replayed the same season twice to apply the necessary tweaks and ensure the tactic works great. With Viitorul I have won all the games in the repeat season (check screenshots below).
It's important to understand that you might need at least 6 months for the players to really get into the tactic; even for Barca this tactic is a bit extreme.
This is the successor of my tiki-taka tactic for FM14.
Very Important: The MCR should be the one executing the corners and free kicks; if the he doesn't, the set pieces fall apart.
For the inside forwards you need players with opposite preferred foot to their position.
You must have players with good anticipation, composure, concentration, decisions, off the ball, teamwork and work rate. "Good" is relative to how good the opposition teams are, but usually 14+ is excellent. Passing is important just for players who will make through passes, basically the MCR (your playmaker).
It's recommended to have players with 2 specific PPM: "plays one two" and "comes deep to the ball". If your players don't have these, you should train them for that. The central defenders don't need these though.
Also the MCR (playmaker) will benefit from having the "dictates tempo" PPM.
For team-talks I usually go with a passionate approach, but if you have a good assistant manager let him handle it.
No need for opposition instruction.
Training: fitness-hard in the preseason, and balanced-average in season.
Match training: tactic at 20% in season, max in preseason.