Rare Candies -No idea, can never be sure you've found them all so cant count them Larvitar -Trade from Fire Red/Leaf Green, you can catch it in the Seavault Canyon
thanks for the post... anyways, since he answered the second question, i'll answer the first. there are exactly 8 visible rare candies throughout the entire game. how many buried rare candies is unknown.
well, it depends on the people ur fightin. if u keep on competing over and over again, then u might see the same trainers with the same pokemon. (well, thats what i see) i can say that when u fight Tucker the Superstar, then u can use strong ice-type pokemon to take down Salamence and Charizard. Then use a grass-type pokemon against Swampert. Remember, Swampert is part ground-type, so electric-type attacks won't work. hope this helps.