Attack and speed combo (sinnoh) - route 206: ponyta, zubat, machop, kricketune, stunky, larvitar(ms poke, but doubt anyone will waste the chance to catch a larvitar).
Attack and HP (kanto) - cerulean (in front of cc): wooper, krabby, goldeen.
Attack and Speed (johto) - Amazon Forest entrance (from olivine port to dock island): arbok, ekans, rattata, aipom (no other pokes there so good spot imo).
Attack (hoenn) - Jagged pass: machop, mankey, primeape.
Speed (hoenn) - route 103: wingull, zigzagoon (recommended for low level or naturally weak pokemon, magikarp for example, as the pokes there are very low level).
Spdef (sinnoh) - route 204 (surfing): tentacool, tentacruel, lotad, lombre, politoed (no other pokes here, all spdef pokes besides one ms poke)
Just a few I've used, some may have already mentioned but i'm not going to bother looking through 23 pages to discover that.