Magnezone: Catch or import a Magenemite (they swarm Fuego Ironworks), then get it to Magneton at level 30. Go to Mt. Coronet. Level your Magneton, and it will evolve.
Lickilicky: Catch a Lickitung (they swarm Lake Valor), then get it to level 33 to learn Rollout. You must level Lickitung with the move Rollout learned to get Lickilicky.
Rhyperior: Get a Rhydon by leveling a Rhyhorn (Route 227 and Stark Mountain) or catch Rhydon (Routes 227, 228, and Stark Mountain). Then, trade it while it holds the item Protector. It will evolve into Rhyperior.
Tangrowth: Get a Tangela (swarms on top of Mt. Coronet), then get it to level 33 to learn Ancient Power. Level it with that move to get Tangrowth.
Electivire: Import Elekid or Electabuzz, or catch Elekid on Route 204 South-Valley Windworks with Pokemon Fire Red in your DS. Trade Electabuzz while holding Electrizer to get Electivire.
Magmortar: Import Magby or Magmar, or catch Magby on Route 227 or Stark Mountain with Pokemon Leaf Green in your DS. Trade Magmar while holding Magmarizer to get Magmortar.
Togekiss: Import Togepi or Togetic, or catch Togepi on the small island on Route 230 using Pokeradar. It is rare but easily caught with Max Repels. Use a Shiny Stone on your Togetic to get Togekiss.
Yanmega: Import Yanma or catch Yanma in the Safari Game. Get it to level 33 for Ancient Power, then level it with that move for Yanmega.
Leafeon: Import Eevee or catch one in Trophy Garden (rare), or get one from Bebe in Hearthome City. Level Eevee next to the Moss Covered Rock in Eterna Forest to get Leafeon.
Glaceon: Get an Eevee, and level it next to the Ice Covered Rock in the snow, on the route south of Snowpoint City to get Glaceon.
Gliscor: Get a Gligar (Routes 206, 207, 214, 215, 227, and Stark Mountain with Pokemon Emerald in your DS), then trade it at night while it holds a Razor Fang to get Gliscor.
Mamoswine: Get a Piloswine from an egg or Swinub that swarms Route 217, and evolve it at level 33 to Piloswine. The only way to get Piloswine with the attack Ancient Power is from an egg. You must level up Piloswine with the Ancient Power move to get Mamoswine.
Porygon-Z: Get a Porygon or Porygon2. Trade Porygon while holding an Up-Grade, then trade Porygon2 while holding a Dubious Disc to get Porygon-Z. Porygon are rare in the Trophy Garden.
Gallade: Get a male Kirlia, and use the Dawn Stone on it to get Gallade. Kirlia is rare with Pokeradar on Route 203 and 204-south. Ralts is also found in the same way.
Probopass: Level up a Nosepass (swarms Route 206) inside Mt. Coronet. It will evolve into Probopass.
Dusknoir: Trade Dusclops (rare with Pokeradar on Route 224) while holding the Reaper Cloth to get Dusknoir. Duskull is found in the same way as Dusclops.
Froslass: Have a female Snorunt (rare with Pokeradar on Routes 216 and 217 and the grass around Lake Acuity). Use the item Dawn Stone to get Froslass.