You know... this board is for Ruby, Sapphire and Emerald - not Fire Red/Leaf Green.....
I sort of wondered the other day when you started that thread about Raichu and Electabuzz, since Electabuzz doesn't show up in R/S/E. But I just figured you were going to trade one in to an R/S/E game. But yeah - if you're playing Fire Red or Leaf Green, you're on the wrong forum. The FRLG forum is over this way -
http://www.serebiiforums.com/forumdisplay.php?f=46
That out of the way, as long as I'm here and the thread's here -
Of the four, the one I'd be least likely to use is Pinsir. It has great stats, but bug type is a problem since it basically can't ever get a stab move.
If I was just going to pick one, it'd be either Aerodactyl or Rhydon. They're both awesome and can take a lot of physical hits and do a lot of damage. Aerodactyl gets stab on rock and flying and gets good moves in both, while Rhydon gets stab on rock and ground and gets the same rock moves. The one problem with Rhydon though is that the only ground move it learns naturally is Earthquake, and that's at level 58. Until then, you have to make do with Dig, and have to use a TM just to get that. But Rhydon can also learn Brick Break, and can simply demolish normal types.
If I was going to pick two though, it'd probably be Aerodactyl and Machamp. Aerodactyl and Rhydon overlap too much and the one big advantage to Rhydon is Brick Break, which Machamp does better.