All materials needed to get every obtainable ribbon on a Pokémon:

--Gen III--
1 GameCube
1 Pokemon GameCube game (Colosseum or XD)
1 GameBoy Advance to Gamecube Link Cable
1 Game Boy Advance
1 Completed Gen III Hoenn Game (RSE)
(Preferably with a fresh battery so you can make berries, which makes contests a lot easier)

--Gen IV--
1 DS Phat or Lite (needs the GBA slot)
1 Completed Gen IV Sinnoh Game (DPPt)
1 Completed Copy of HeartGold or SoulSilver
1 Action Replay (optional, it's needed to use AltWFC to get the World Ability Ribbon)

--Gen V--
1 Completed Gen V game (BW, B2W2)
(There are no ribbons in Gen V, but you need the game to transfer to Gen VI)
(You need a second DS to transfer, but you should have a DS Lite and 3DS if you have all the materials)

--Gen VI--
Pokebank Subscription
1 2DS or 3DS
1 Completed Copy of X or Y
1 Completed Copy of Omega Ruby or Alpha Sapphire

--Gen VII--
Pokebank Subscription
1 Completed Copy of Sun or Moon

Finally, a lot of patience. Good luck!