5X > 5A > 8[Y]
258 damage on wall.
(too good)
A lot of characters, mainly in Power are capable of basic strings with this level of damage. Damage scaling pretty much sets a stone ceiling in this regard.
Anyway, it seems the main hurdle of playing Gardevoir is how to deal with guarding. None of her projectiles cause stagger and she can in fact stagger herself if she hits them with the wrong moves.
In field phase you'll be using charged forward ranged quite a bit as it pierces counters and deals significant push on block. In duel, using Psychic or Future Sight (low) can be great for forcing jumps that are easily shot down with her anti-air if you threaten with her back-x, which inflicts a huge amount of pushback and block damage especially when charged.