Shadow Punch was introduced in Gen III, and was never a TM.
The Good Ol' 8-bit days had lots of weird TMs, though, like Explosion, Selfdestruct, Water Gun, Seismic Toss, and even Dragon Rage. The elemental beams (Flamtethrower, Ice Beam, Thunder bolt), their stronger relatives, Along with Rest and Double Team, have always been around as TMs, and even keeping their number through all these years!
Gen 2 had weird ones too, and the TMs have stayed the same since Gen 3, only havng the number rise from 50, to 92, between Gen III and IV.
All there's left to do is see what Gen V has in store for these TMs (Or, according to Pokemaster's B/W leak, the "HMs").