Pokkén Tournament is a very unconventional fighting game, taking elements from both traditional 2D and 3D fighters. Its system mechanics are simple to pick up, but there are plenty of nuances for experienced players to optimize their gameplay.
The interface in Pokkén Tournament is drastically different from traditional fighting games, being inspired by the mainstream Pokémon games instead. Information pertaining your character is located in the bottom left corner, while your opponent's stats are at the top right. There are a couple of HUD elements that you need to take into account while playing.
The long green bar is easily the most eye-catching element on the screen and for good reason, as it represents the remaining HP of your Pokemon. The goal of the game is to completely deplete your opponent's HP using your own attacks. Every Battle Pokémon in this game sports different HP values. Frail and speedy characters like Pikachu tend to have lower HP, while slower and powerful Pokémon like Machamp have more health to spare. Along with your main HP, there is often a darker green bar extending from it that represents recoverable HP, also commonly known as "white health". White health represents how much HP you can regain through certain actions, most notably assists and phase shifts.
At low HP, you may notice that your HP gauge and number turns red. This indicates you're in "guts" or "rage" mode. While in this mode, your Battle Pokémon gains greater attack and defense, so it can be a valuable opportunity to stage a big comeback.
The timer is at the upper left side of the screen and tends to be ignored during gameplay. It is an important factor of the game to prevent two defensive players from dragging a match on forever. The default timer value is given at 80 seconds, but that can be adjusted or removed altogether. When it nears 0, a short alarm will play and the timer will begin to glow red. Once the timer reaches 0, the round ends and the winner is determined by the Pokemon with the highest HP. This is calculated by taking the percentage of remaining HP compared to a Pokémon's max HP, so in the case of two Pokémon ending the match with the same HP value, the Pokémon with the lower maximum HP shall win.
Circling the player portrait is the Synergy Gauge, a meter used for a central mechanic of the game: Synergy Bursts. There are many ways to increase the gauge, mostly through phase shifts, sponging attacks with counters, or using certain Support Pokemon. When it reaches full, you can activate Synergy Burst, granting Battle Pokémon specific enhancements to your character to shift the tide of battle. The duration of the Synergy Burst can also be determined by the remaining meter in the gauge as it drains out. If the gauge is glowing while in Synergy Burst, it means you can perform a Burst Attack, a powerful super move that does a ton of damage.
Above the Synergy Gauge is the Support Gauge represented by a circle with an image of your chosen Support Pokemon. This gauge builds up automatically with time, and lets you summon your Support Pokemon when it is full. Different Support Pokemon have different gauge build-up rates.
Below the HP gauge are a number of circles depending on how many rounds are needed to win, with the default set to 2. Upon winning a round, one of the circles will light up for the winning player. The match ends when all of a player's circles light up.