There are pegs on the Bakugan and there are corresponding indentations on the Bakunano.
paige
they are the 4th series of bakugan version of battle gear
Dual elfin can't combine with other bakugan , but elfin can combine with klawgor and scrapper.
No they can not combine.
The only bakugan you can combine are 6 traps and a dragonoid or 7 traps to make a Helios but in battles you can combine 2 or more bakugans G's
Yes, there are several combiners.
No you have to match your power to the numbers on the side then add together to see who wins the battle! Only match the colors with BakuNano's
some bakugan traps can combine also if you have neo dragonoid and 6 other traps then your able to create maxus drago
slingpike
Only the Mechanical Bakugan of the vexos combine... Marucho's just has Elfin and Tripod epsilon. Bakugan that combine will have tiny tabs so they can fit together.http://www.bakuganbay.com/Bakugan-Battle-Brawlers/Combat-Set
yes for exsample you can use a darkas reaper and a aquas mantas together in the show they don't but you can
Possibly Yes or at the same time maybe No. So it seems that if there will be a season 5 it will be called Tech Masters or something like that. I'm a Huge fan so hopefully... OK just watch out for new episodes do not trust that weird February stuff. Wrong there will be one its already released in japan and the bakugan toys are called bakunano