I just want to know what weapon each companion is most effective with. Currently I have Boone, Cass, Verinoca, Raul, and Arcade. I tried to give Boone a Riot Shutgun, but let's just say that, that deathclaw was the last thing he never saw...

Raul does best with the Medicine Stick or a Brush Gun. As a Vaquero he gets a perk to fire faster with cowboy weaponry.
Cass does best with a hunting shotgun, albeit with slug rounds. She has the shotgun surgeon perk. I specifically suggest a hunting shotgun and slug rounds because it makes it easier for her to punch through DT.
Boone does best with a sniper rifle. He does NOT have the strength for an AMR, hence a custom rifle like the Gobi or Christine's sniper is best since he misses a lot with an AMR. I give him the Gobi because, iirc, Christine's sniper's silencer doesn't work for him. Boone's crit rate is decent thanks to his beret so he will crit with the Gobi on occassion.
Veronica does best with Pushy, as it has the highest DPH behind the Ballistic fist, which she lacks the strength for.
Lily does well with Oh Baby!
Arcade? Anything he can handle, tbh. I found him surprisingly capable with the YCS/186, which makes sense due to it's low STR requirement and his skill in energy weapons.

pay keen attention to the ST requirements on the weapons, as many of the higher end weapons, like the AMR, Gatling Laser, Riot Shotgun etc, are too heavy to be used properly by most companions

for example, Veronica has a ST of 7 I believe and the Gatling Laser requires 8 ST to be used effectively, but if you put her in Power Armor (+1 ST) she will use it fine, more than fine actually, she mows down NCR Rangers

another tip is to keep the ammo in mind. Keep multiple ammo types for your companions for different situations for example, if you have a shotgun on Cass (you do have a shotgun on Cass right?) keep it loaded with Magnum or better yet Slugs to cut through the heavy armor on Deathclaws or NCR Heavy Troopers. On the other hand, give Boone some .308 Hollow Point to really punch holes in those Cazadors and Glowing ghouls.

For Veronica, Bulk Ammo for energy weapons may seem cost effective but youre hurting yourself as bulk ammo lacks the special properties of higher (or normal) energy ammo like armor piercing along with lower base damage to boot


you beat me to it. Just to clarify: Raul gets the Vaquero perk only after completing his [unmarked] companion mission and even then only depending on the right conversation choices. Also, it's easy to forget but Veronica also has Energy Weapons tagged and is DEADLY with a Plasmacaster or fully modded Gatling Laser