Hmm...no. If anything, Ash will use his reserves for the League, which is highly unlikely, as he's doing a fresh start again. Meaning he'll want to use only the Pokémon caught this region.
There could possibly be a Whirl Island-esque mini saga, or a Battle Frontier-esque mini saga.
If the former, no old Pokémon will return, but we may get some old character appearences.
If the latter, I can see Ash switching with a few of them. But in either situation, Butterfree and Primeape are never going to return, along with Lapras and Pidgeot. If they are ever going to, it will be at the very end of the show, and we'll see some sort of magical reunion.
If the next mini-saga is Battle Frontier-esque, I'd like to see some that weren't used in said mini-saga. Namely the Johto starters, who could all use some major Torkoal-ish battles. Tauros may have already been used, but I didn't like waht they did with him. Him, Muk and Kingler should be brought back to battle, since...Muk hasn't done anything since the Silver Conference, and Kingler hasn't done anything since the Whirl Island Cup (Johto League doesn't count, since he was never actually used.)
So yes.
My list of reserves to be used in the next mini-saga are:
Cyndaquil - Either give it some amazing new attacks or evolve it. Preferably both.
Bayleef - Doesn't need an evolution, but a fresh attack would be welcome.
Totadile - Good showtime needed. He always had an amazing battle style, with his energetic dancing helping him dodge attacks. I'd like to see this trait follow into any future evolution.
Muk - Needs some battling that doesn't involve "His body reflects attacks" or "Sludge Bomb!". Shadow Punch? Or even, if we're lucky, some of the new D/P poison type attacks.
Kingler - No spotlight in a long time, and last time it was seen outside of Oak's, it got shafted for a Squirtle appearence. I'd like to see one of Ash's Pokémon with Guillotine, or possibly show the difference between Kingler and Corphish.
Tauros - Don't think he got enough time to develop last time, and Double Team wasn't a welcome attack for me. I'd have preferred something else, and hopefully if it does appear we'll get to see that.
So now onto the Pokémon I want Ash to capture. Well considering he already has four Pokémon with him, and the writers are on the new craze of only giving him six at a time, I'm only going to guess two. One is the most obvious thing ever, but both have uses.
Buoysel - It's been speculated hundreds of times, but it has a base. It's one of the few that can battle on land of the normal Water Types. It is a Pokémon that includes Ash's usual style of Pokémon with a physical asthetic attitude present. Take Grovyle/Corphish. They both had a certain...ignorant demenour about them.
Sukatanku - While not one of Ash's usual types, it posesses Flamethrower, an attack which Ash likes using. Alone with Slash, Blade Test and some possible Egg/TM moves involved, it will become a volitile powerhouse in hte likes of Heracross and Glalie.
Iota