Ok, now going on to what beys would be like if they were made of different metals
Magnesium:
ooooohhhh-ahhhhhhhhh, sparks, love em' magnesium sparks when it it hits another metal, so given how you would count that as fun, it is cool and not cool, good fact is they FREAKiNG SPARK, EPIC!!!!! not cool part is that that results in a fire hazard, or burn hazard. another not cool thing is that magnesium is brittle, and so it could snap more easily, and finally, magnesium is the LIGHTEST metal in existence, so beys would not spin as long, beys would weigh about 38% less than they do with the standard metal used.
Titanium:
Not bad, actually the bey would weigh roughly 44% more than it did before, given how titanium can bend crazy without losing shape, if could work for long-term use as well, only issue is titanium costs more than aluminum, so it would cost much more, beys that were about 21$ would cost about 30$, huge increase in price, right?
Chromium:
Ooh! Shiny!!!! chrome would be nice, its tougher than aluminum, and not to mention, shinier. It also would make fusion wheels weigh over 2 TIMES AS MUCH, which means the bey could battle for longer, which means that bey battle times would go from 2-5 minute battles, to 3-6 minute battles, making more fun, especially if the beys are attack types. Weakness, chromium costs, alot, it would make the average bey cost around 35$, which compared to normal prices, thats rather expensive.
Tungsten:
So HEAVYYYYY!!!!!!! Yup, tungsten weighs alot, an average bey's weight (25 grams) would increase to upwards of 80 grams! now not only would it DRAMATICALLY effect the bey's weight, but it would increase stamina due to momentum. beys could battle for longer because it would withstand more attacks, and beys could be launched at a much higher speed without reaching terminal velocity (The highest RPM that the bey could withstand) only issue is, with a heavy bey, means the need for tougher gears in ripcord launchers (this is not an issue with string launchers, but string launchers with a heavy bey can take tremendous strength) if you have used basalt diablo horogium, or diablo destroy, you will know what i mean. you strip gears like mad.
Although this would not be a hard fix, given you could just use metal gears for the launcher.
for those who want to know how long a battle could last with tungsten fusion wheels here ya go:
5-8 minute battles!
and BEST of all the features
the bey would not cost much more than it does already, only about a 2-3$ increase in price, which for what you get, it would be worth the extra price.
Now, this metal would be best for any bey, but would cost crazy!
Iridium:
Beys would have even MORE dramatic weight increase than tungsten, same exact result, only even better. issue is iridium is about 900$ for just 10 grams, which is not enough to even make the smallest fusion wheel, it would take roughly 115 grams of iridium to make a standard fusion wheel. so it would cost thousands of dollars to make it.