Trying to catch Kangaskhan in Blue. Whenever I throw bait, poke balls miss and whenever I throw a rock, it decides to run. How would I catch it? It's the last Pokemon I need for the Pokedex.
In general, both Rocks and Bait actually make catching Pokemon less efficient. Often the best way to succeed in the Safari Zone is to simply throw Balls until the Pokemon catches. If you want to know why this is the case, read the Cave of Dragonflies' excellent article; if you just want to know what the most effective strategy is for your target, use the Safari Zone calculator.
In the OP's case, the most efficient way to catch Kangaskhan is to look for it in Area 1 with a 4% encounter rate at Level 25. Assuming you still have all 30 of your Safari Balls, the chance of you catching Kangaskhan before it runs away is 14.62%.