Many powerful fighters populate the huge cast of Bleach, from the black-robed Soul Reapers to the mighty Arrancars and the deadly Quincy. One of Ichigo's best friends, Uryu Ishida, happens to be a Quincy archer himself, one who fights loyally by Ichigo's side to protect their friends. On the other hand, of the series' greatest villains is Grimmjow Jaegerjaques, one of the Espadas and a thuggish minion of Sosuke Aizen's. He and Uryu never crossed blades in the original story, but if they did, the result would be a high-octane battle between natural enemies, a high-level Quincy versus a powerful Hollow. Pitting Uryu's advanced archery skills and cunning against the speed, power and agility of one of Ichigo's greatest rivals would've made for a legendary fight, but still one with a clear likely winner.
Uryu's Powers & Abilities
Uryu is a Quincy, and that fact alone means he has access to a wide variety of powers and abilities. To begin with, Quincy can see Hollows and Soul Reapers, despite not being souls themselves, and they are primarily ranged fighters who can manifest bows and arrows of spiritual energy. Uryu shoots with astonishing precision, and he can either fire a single, powerful arrow -- as he did during a fight with Captain Mayuri Kurotsuchi -- or a swarm of smaller arrows to overwhelm his enemies. Uryu can fire as many as 1,200 arrows at once, and his Licht Regen technique is his most efficient way to turn that power on an enemy, as he did on Ulquiorra Schiffer. What's more, Uryu can use his arrows to knock his enemy's own projectiles off course, which he actually used against a Soul Reaper's Shikai.
In case of emergency, Uryu has a Sanrei glove that greatly enhances his power temporarily, at the cost of eventually draining his Quincy abilities and leaving him powerless once the fighting is done. He used the glove to get the edge on Captain Kurotsuchi, and if he's fighting just one final battle, the price may be worth it. Beyond that, Uryu also has a short spirit blade called the Seeleschneider, which can shred spiritual energy in the air and allow Uryu to absorb it, which is an exceedingly Quincy thing to do.
To get around, Uryu can use the Hirenkyaku technique, which creates a smooth disk of spirit energy under his feet that he can skate around with, performing a move similar to the Flash Step or even an Arrancar's Sonido. It's not quite as fast as that of Captain Byakuya Kuchiki or Yoruichi Shihoin, but it was enough to take Szayelaporro Grantz by surprise. Uryu can also perform Ransotengai, moving his injured or exhausted body with spirit strings, like a puppet.
Grimmjow's Powers & Abilities
Grimmjow is the 6th Espada, putting him amongst the Arrnacar elite, and he's truly earned that rank. His Sonido is fairly fast, though not as fast as Zommari Rureaux's, and he has immense speed, strength, agility, stamina and fighting instincts, making him an excellent melee fighter. He can keep up with Ichigo's Bankai, both with his sword and just his bare hands and feet. Grimmjow's habit of firing destructive red Cero blasts from his palms is definitely handy, but he can also charge up a Gran Rey Cero to utterly obliterate his foes.
His Zanpakuto release is Pantera, turning him into a panther-man with heightened offensive power, agility, Sonido and endurance -- and it was even stronger than Ichigo's Hollow mask form, for a time. Grimmjow can also fire incredibly destructive mini-missiles from his elbows and use Desgarron to create ten giant claws that attack the enemy.
The Winner: Grimmjow
Uryu's ranged attacks, spirit energy harvesting abilities, Hirenkyaku and Rasontengai will all keep him in the fight for awhile, and Grimmjow would have to take his Quincy enemy seriously to win. Uryu could keep pace with Grimmjow's movements at first, and have his Espada enemy on the defensive with arrows. If Grimmjow fires back with a Cero, Uryu could either avoid it, or use Seeleschneider to steal some energy and charge up his own attacks. He'd be all good until Pantera comes out.
Pantera would change everything. In Release mode, Grimmjow would become too quick for Uryu to handle -- he'd easily outmaneuver Uryu and deliver bone-crushing attacks up close. Desgarron may not be a good idea, since Uryu could harvest some of its power with Seeleschneider while avoiding the worst of it. But Grimmjow probably wouldn't try it at all; instead, he'd deny Uryu the chance to use Seeleschneider in the first place by sticking to melee attacks, which is where Grimmjow shines, anyway. Even Uryu's use of Ransogentai wouldn't help him survive for much longer, and he'd quickly be forced to admit defeat.