Pikachu:
Grass Knot:Deals with Ground Types,the heavier the foe,the greater the damage.
Focus Punch:Good Power,I'll tell you the eay way to do it...
Double team:Keep using this and then try Focus Punch and because you will have high evasivness,the foe is more likely to miss,then you can continue focus Punch.
ThunderBolt:Good power,Good accuracy.Can cause Parylyis(Spelling?)
Vigoroth:
Double Team:I'll tell you why...
Focus Punch:Keep using Double Team until you think you should use this,just like Pikachu.
Aerial Ace:Deals with Fighting types.
You can choose this last move because I'm not sure.
Porygon2:
Tri Attack:Can Parylize(Spelling?)Freeze or Burn the foe.
Hyper Beam:Try some PP ups for this move.Great power.
Psychic:Deals with Fighting Types.
Conversation2:Changes type to last move used by the foe to make it resistant to the move.
Jigglypuff:
Sing:Puts the foe to sleep.
Dream Eater: Deals with sleeping Fighting types.High power.
Hyper Voice:GREAT power.Very Useful.
Double edge:Does recoil damage so have some berries and potions handy.
Squirtle:
Ice Beam:Deals with Grass Types.Chance to freeze.
Dig:Deals with electric types.
Hydro Pump:GREAT power.Try some PP ups.
Rain dance:Makes Hydro Pump even MORE powerful.
Sorry,can't think of anything for Ivysaur...