This guide will mostly point out and discuss the characteristics and advantages of high mode, since low mode is basically the same standard height of all Beys in the Burst series. Now let's take a look at what they are:
1. Increased Stamina vs Low Mode
This is especially apparent in the DB Standard Beystadium due to the deeper curvature. While in high mode, if the opposing Bey is in low mode, the high mode Bey will be able to tilt downward and apply more pressure to the opposing low mode bey. If both beys are stamina-types, then there'll be a HUGE advantage for the Bey in high mode. The high mode Bey will wear down the low mode Bey and have a higher chance of winning with a final spin.
2. Downward and Blade-to-Blade Attack Strikes
Since high mode Beys will tilt their posture, this mode is preferred for top-heavy attack combinations that you build. This will help your combo strike low mode Beys and possibly make them scrape. This could help you penetrate their defenses and drain their stamina. But that's not all-- if you find that the opposing Bey your opponent is using will probably be played in high mode, you'll want your attacking Bey in high mode so that it can make blade-to-blade contact against the opposing high mode Beys.
Again, this will take knowledge and an educated guess based on what parts are in your opponent's combo, since bladers are technically allowed to change modes at the beginning of the battle, after both players reveal their initial combos.
3. More Attack Mobility
The DB Standard Beystadium is a larger stadium, but even on the older B-33 stadium, you might have an attack combo that you'll need to move lightning fast around the arena in order to KO the opposing bey. Being in high mode will help you with this goal since the expanded weight distribution and tilting posture will generally force your Bey combo to move around more than if it was in low mode. This is easy for you to test out, so if you'll want to launch your combo several times in low mode and then again in high mode to see if it will get the extra boost of speed and mobility you're looking for.
4. Defense Gap & Forge Disc Attack
This is literally a double-whammy of an advantage! If your opponent's Bey is an attack-type or balance-type that is best in low mode, you can switch your Bey into high mode to create a gap in the middle that will help your bey's blade/energy layer avoid being hit by the opposing bey's blade. Also, if you want to try and use your forge disc as a secondary attacker, put your bey in high mode so that your forge disc has an increased chance of making contact with an opposing bey's blade/energy layer in low mode. This can be especially brutal if you're using a right-spin combo with the Karma forge disc-and it's terrorizing spikes-- yikes! That's some gnarly Metal Fight action right there!
Bottom line: experiment with using your forge disc as an attacker or a defender based on your combo!
5. Disadvantages?
The one slight disadvantage to be aware of in high mode is the tilting posture of the combo. As we mentioned earlier, this characteristic is generally a positive bonus when used properly, but be aware that it might hinder your combo depending on the parts you use, and the opponent's Bey. As always, only testing and experience will help you figure things out.