Before building an arsenal you need to figure out what you are building an arsenal for: League or house patterns, travel league or multiple houses, Tournament bowling, or Sport/PBA pattern leagues or tournaments.
For a regular house shot league you will need 4 balls:
1. A Heavy oil ball for when the machine goes nuts and puts down a flood, it happens. Suggested Balls to use: Cell, Buzzbomb, black Widow bite, Special Agent or Attitude shift or Passion, or columbia resurgence, MoRich LevRG. Brunswick Twisted Fury.
2. Benchmark ball. This is an everyday ball used for most medium conditions. Suggested balls: Columbia Rival or momentum, Any of the Nv series from Ebonite, Hammer Black Widow, or Toxic, Lane#1 Super Nova, MoRich NsaneLevRG, Storm Secret Agent, or Rapid Fire, Legends/LaneMasters Black Pearl. Brunswick Fury Pearl
3. Dry Lane ball for when you show up and the lane oiling machine is broken. Suggested balls to use: Columbia Jazz, Ebonite Bash, Hammer Vibe, Lane #1 Supernova xp or Liberator, Legends/Lanemasters Hornet, Brunswick Groove DryR or Power Groove.
4. Spare Ball DON'T LEAVE HOME WITHOUT ONE.