blazikenlv100, isn't there another Grass move you can teach him besides Solarbeam? Solarbeam's a bit unreliable...
Here are some ideas for Shiftry:
http://www.smogon.com/rs/pokemon/shiftry
As for Weezing? If you can't get Pain Split, you should be able to get Will-O-Wisp at least. And if you are really worried about status conditions on Weezing, then teach it Rest and give it Leftovers - Weezing needs those Leftovers to stay alive perpetually, and Rest will heal off all status.
(To get Willowisp, breed Koffing with someone from the Shuppet or Banette line. To get Pain Split, breed it with Misdreavus instead. Getting WOW and Pain Split on the same set wasn't possible until Gen 4, when WOW attained TM status.)