they will ask you
No, I'm afraid that the Pokemon Battle Arena is only for DS battles, not for trading, but there is a place where you can trade, battle, and communicate.
You have to trade it.
give it a protector and trade it
You spend 25 credits buying it or trade
It's a battle game, not a story mode. Trade back to your game to evolve YOUR Pokemon. You can't touch the rentals.
Link trade!!!!!!!!! You have to trade for another Haunter in order for it to evolve into a Gengar
It depends on who your battling.
you go on Mibit to show of your Pokemon then after you put it up for trade and someone offers then you can accept or decline.
You can buy the TM for Earthquake at the Battle Tower/Battle Frontier.
Yes
go to the vally windworks trade for it or battle someone who has it
You need to go to the trade centre and then select 'trade Pokemon'. then you can either choose to put one of the Pokemon in your party up for trade or you can browse the trades that are already up. Do not thank me. I give this answer as a service not anything to do with money or honour.