The Long-Range Princess, Gardevoir... Most know her as one of, if not the worst, range spammer in the game. This may be true, but she's still a very offensive character up close. Most don't think about this as they only focus on countering her range to get in close, but this could end up being their downfall.
First, Field Phase - some would argue this is Gardevoir's best area to deal damage, and technically speaking they're right. Her ranged attacks link up and harass the opponent so well, it isn't too surprising that people would want to abuse this during the fight. Her standard Y/Range option is a small orb of psychic energy, and although it moves slowly, wasn't intended to hit the opponent per se, but put them into a better area for Garde to handle them with. Side Range is a flurry of three psychic energy discs, moving relatively quick and covering a wide area, as well as letting Garde move quickly. Her Back Range is an anti-air, and will immediately begin a phase shift when they hit their mark. All of these, bar the Forward Range which IS the link up attack, is a quick psychic arrow shot. When used alone as Forward Range, deals damage and stuns the enemy for a brief moment, but it can also be charged. When charged, alone or by linking up, it not only pierces counter attacks, but stuns them for a couple seconds, allowing you time to close the distance or continue harassing with ranged options. This is definitely where Garde prefers to fight, since her attacks are so synergized with each other and can deal massive damage overall. Her Pokemon moves here are the same as in Duel Phase, so they'll be covered there, except Aerial/Jumping which is Magical Leaf, creating multiple homing projectiles. Great for harassment and encouraging shields.
Duel Phase - Most new Garde players don't like being here long, so they play super defensively. Garde however, prefers offensive here. She has a multitude of ranged projectiles, even in Duel Phase, to keep the opponent at bay, but has plenty of tools for if they manage to close the gap. Let's start with her standard/Y attacks. Neutral is your basic combo, which can be cancelled into any Pokemon Move/Pmove, and usually ends with Psyshock. Down y is a quick gap closer, also allowing combo follow-ups. Up Y is and anti-air, same as her anti-air ranged attack, but shoots in three directions as well. And finally her Back Y, a quick projectile that can knock opponents back. Then comes her Strong/X attacks, most of which while powerful are also slow. Most notably, her Back, Neutral, Down, and Forward. Back X is chargeable, and deals massive shield damage, breaking it easily if fully charged, and with chances to follow up with down Y to neutral Y combo, if the enemy lets you. When charged fully it also pierces counter attacks, so that's good too. Down X is a very low spinning projectile that pierces counters, or trips the enemy if they don't guard or counter. Another excellent ranged harassment tool. Finally, Forward and Neutral, both are an orb attack at close range, just Forward X advances forward. Both combo into Stored Power, another Pmove. Then Garde's air game comes into mind. Jump X is a vertical dropping attack that combos into Neutral Y flawlessly when successful. She has a jumping counter attack as well, just by using counter in mid-air. If using a Pmove, or A, in mid-air, Garde uses Magical Leaf, a downward diagonal beam attack. Up and Down A is Future Sight, causing a powerful attack either at the ground or in the air, wherever you input. Forward A is Stored Power, an attack that increases in range and power for each Calm Mind you have stored up. Speaking of, Calm Mind is her Back A, and transitions into four different options. B lets her teleport into mid-air, with some directional influence, which can then transition into any aerial option. X is Psychic, which follows the opponent and explodes after a moment. Y is Energy Ball, which moves slowly but can be hard to avoid, but when hit with a ranged attack or projectile, splits up into small homing energy attacks, or if Y is input again, it splits up horizontally in Field or vertically in Duel Phase. Finally, A. This input is a powerful counter attack in a dome shape, called Dazzling Gleam. Great for attack spammers and people who rush opponents down. Blaziken and Weavile come to mind.
Garde has one other special trait, being a slight hover/double jump when R/Shield is input during a jump or after using Teleport. This transitions into any aerial attack.
Overall, 8/10 is my grade for Garde. Great range game, great close combat potential, just with below average HP and somewhat slow attacks and end-lag on many of her moves, she definitely prefers range to close quarters.