Wild Arms 4

The "Gene Driver" is a bit of a colloquial term for those people who can use ARMs, such as Jude Maverick, and, to a lesser extent Yulie Ahtreide. They are highly prized individuals sought out by the various military organizations for their power.

The "Gene Driver" term has been retroactively applied in some media (such as the Japanese web site) to apply to anyone who can use an ARM, even in those Wild Arms media (like Wild Arms 3) where using an ARM just isn't all that uncommon.

Wild Arms

Both Rudy Roughknight and Jane Maxwell could be considered "Gene Drivers", as could Magdalen Harts. In Rudy's case, it's because he's artificially cloned using the "Holmcross", while Jane and Magdalen are both natural "Gene Drivers".

Wild Arms 2

While no special mention is made of either Brad Evans, Ashley Winchester, or Judecca Ducet's ability to use ARMs, they seem uncommon in the setting. Based on either the game or the background media, it's impossible to be conclusive.

Wild Arms 3

All four main characters, and many of the villains, use ARMs. The "Gene Driver" aspect of the franchise doesn't seem to apply to anyone here.

Wild Arms 5

It's explicitly stated within the game that everyone is given ARMs for their protection by the Veruni. So, again, the "Gene Driver" aspect of the setting is lost.

Wild Arms: Twilight Venom

Only two true "Gene Drivers" exist, so far as anyone knows, being Irving Vold Valeria and Sheyenne Rainstorm. In addition, the gene-spliced clones of Gina Angel and Judecca Ducet, as well as the final clones of Keanu Fallwind and Laila Belle are Gene Drivers, to limited degrees of success.

Wild Arms: XF

Though several special weapons are 'linked' to their users, this doesn't appear to be the same trait as a Gene Driver, but rather a function of crafting the weapons to their specific bloodlines.