Availability only plays a tiny part in tiering/class.
CS completely outclasses WB, (I believe it has better stamina, as long as it's a good one (basically, most CS's from unicorno starters are aggressive and have poorer stamina than those from the Unicorno Booster and BB-100 CS beys). Also, with the release of Ray Striker by hasbro, it won't be hard to find, and it's very easy to get a cheap, pre-opened BB-100 off ebay, with a good CS.
WB doesn't achieve win rates anywhere near CS. Plus, WB doesn't work well with BD145 (in normal mode), generally, as it is too low, and causes scraping.
CS is the most comparable part, and outclasses it. RSF and RS have even better defence (though RS is the best for pure defence), though their terrible stamina/balance compromises their practicality somewhat.
Also, with the "worst attack wheel" Storm isn't the worst, it's outclassed, but it was top tier for a reason. The "worst" is hard to define (especially without a clear explanation of what wheels we should choose from). That said, Escolpio (pre-hws) would be terrible, having no real contact points and light weight. As for wheels that seem aggressive, possibly Killer, Poison, or something from the Legend series, due to light weight, resulting in terrible recoil.