- B1: Bakugan that are 28mm in diameter
- B2: Bakugan that are 32mm in diameter
- Open Core: All B1 Sega Toys, Sonokong, and Spin Master Series 1 Bakugan have an exposed magnet
- Closed Core: All Series 2 B1s, and Series 1 B1s that were re-released have a sealed magnet
- Treatment: A variation from the normal 6 attributed releases. They include translucent plastic, unique color combinations, among other gimmicks

Bakugan releases differ by regions of the world. Below are the identified major regions, though specific countries would obtain specific releases on occasion. The identified regions are as follows:

- Japan (Sega Toys releases)
- South Korea (Sonokong B1s, otherwise part of Asia Region)
- Anglo-America (Canada has slightly different releases)
- Western Europe/Latin America (Nations south of the USA received European waves)
- Eastern Europe/Middle East (Primarily Russia and Post-Soviet nations)
- Asia + Australia (Appears to have received a mix of everything else. Documentation is poor)

Note:
Rarity scores are based on how easy the Bakugan is to find for a primarily American buyer, however Sega Toys and Takara Tomy releases have scores based on their own region. This means that if you live outside of the designated region, increase the rarity score by one or two points.

For example, Hydranoid is 6/10 (Moderate) in the US, and did not release in Japan. If you live in Japan, it is likely 8/10 rarity instead.
If a European Bakugan is considered Common (say 3/10), then to an American, consider it Moderate (say 5/10).
This is is because you would have to go out of your way to find sellers or utilize websites or middlemen, and are also likely to have to pay an increased cost in order to obtain it along with international shipping. This effectively raises your barrier to entry, even if the toy in a vacuum is not difficult to find.

- 1/10 - 2/10 (Very Common): Easy to find and relatively cheap, you will likely find a minimum of 10 results upon searching for one online
- 3/10 - 4/10 (Common): Relatively easy to obtain, slightly less numerous and more expensive. Will find a few results in a search
- 5/10 - 6/10 (Moderate): Potentially annoying/expensive to track down, but realistic enough to obtain without too much issue
- 7/10 - 8/10 (Semi-Rare or Rare): One will pop up every few weeks or months. You may have some competition in trying to obtain this
- 9/10 or 10/10 (Very Rare): Realistically, you will not obtain this Bakugan. Get a custom paint job or a recast. Good luck otherwise
- One-Offs: An anomaly that probably shouldn't exist, but has been documented for the sake of completion