Resistance: Fall of Man
The Hybrid is the generic foot soldier that makes up the bulk of the Chimeran forces. Their strength comes from their numbers as on their own they aren't anywhere near as formidible.
They use the Bullseye as their weapon, but they do not use the secondary application of the weapon as it would probably make the game harder than it already is (especially on harder difficulty settings). However, it's not even necessary of them to, as if there are three or four Hybrids all raining Bullseye bullets, it's very easy to see your health diminish quickly.
In terms of the best weapon to use against Hybrids. We've recommended the M5A2 Carbine and Bullseye purely because they have the most ammo throughout the game and you will encounter a LOT of Hybrids along the way. The M5A2 Carbine takes them down very quickly if they're hit in the head, and the L23 Fareye also has similar results, taking them down in one shot to the head.
The generic Chimeran foot soldier returns in Resistance 2, although this time they are used much more sparingly. Generally they are encountered in combination with something else, and they have much less armour to protect them from the rigours of combat. This could be due to the increase climate of North America though, but they also appear to be much leaner.
The Hybrids still use the stereotypical Bullseye, and nothing else. However, this time they are much more strategic in their attacks. It's very easy to get overwhelmed by Hybrids, as they look to use the new surroundings to their advantage.
As with Resistance: Fall of Man, the Hybrid is susceptible to nearly all types of weaponry. However, due to their marginalised armour in Resistance 2, they are much easier to take down. A good dose of headshots from either the M5A2 Carbine or Bullseye will quickly cut them down though.