I can't do it. I'm too old and have worked too hard for "my ideal" battery to limit myself to just 5 guns, but in the spirit of this thread's question I'll list my ideal 5 (plus a few additions).
Remington 541-T .22 LR with a Simmons 3-9x scope. A good, accurate bolt action rifle that I like for plinking, gophers, and practice shooting out to 100 yards. I have even taken a few mule and whitetail does with it (legal in Montana).
Mauser Mark X in .257 Roberts Improved with a Leupold VX-1 4.5-14x40 scope with their B&C reticle. I built this as my medium size game rifle, but it is great for small varmints out to 300 or so yards in the wind. I have used it for all of my mountain sheep, most of my mule and whitetail deer and pronghorn antelope, and one of my best 6x6 bull elk. I built this rifle in Fancy walnut and the barrel and action are traditionally blued which is not good for very wet hunting conditions.
Weatherby Vanguard in .300 Wby with a Leupold VX-3i 4.5-14x40 scope with their CDS turret tailored to my 180 grain Barnes TTSX handloads. I built this rifle as my primary elk rifle, but it quickly became my favorite rifle that I've also taken on 5 international hunts for animals from 25 to 900 pounds. I also stocked this rifle in Fancy walnut that I don't like to take out in very wet conditions.
Remington Model 700 BDL SS in .375 Rem Ultra Mag with a Leupold 2-7x30 scope. This cartridge is essentially a .375 H&H on steroids that I built to hunt African Cape Buffalo. I have used it on two African hunts for a variety of animals from 25 pound antelope to 1500 pound buffalo, and it is good for anything that walks this planet.
Remington 870 pump shotgun in 12 gauge. This is a great low cost, dependable all around shotgun that with its screw-in choke tubes is a great choice for upland game, waterfowl, and even Trap and Skeet shooting. With its extra rifled barrel with a 3-9x40 Simmons scope it becomes a good slug shotgun out to 100 or so yards.
So there is my "basic" 5 gun battery, but to that list I'll have to add my alternatives:
Remington Model 700 BDL SS in 7mm Rem mag with a Nikon Prostaff 4-12x40 scope. With this rifle's stainless steel barrel and action and its plastic stock it is my choice rifle for wet conditions. This cartridge is good for anything from varmints to moose and I have used it on multiple international hunts in Canada and Africa.
Ruger Super Blackhawk in .44 Rem magnum. Living and hunting for many years in grizzly country, I often carry one of pistols for protection, small game, and hopefully for deer or elk. I did shoot one black bear with one.
Remington Rand Gov't Model 1911 A1 in .45 acp. I have just as many or maybe more miles carrying this pistol as my .44 Ruger. It is great for plinking, small game, deer, and I shot my first black bear with it.
Ruger Single Six in .22 LR is another pistol that I usually carry when deer or antelope hunting in the eastern plains of Montana. It is great for plinking, varmints, snakes, and occasionally a finishing shot on a deer, antelope, or coyote.