My turn- Playing ZA!

Are you allowed to go challenge the Dauntless Raichu Duo without beating the game? And if you can, would you survive?

Tried a ranked battle, out of sheer curiosity. Got second using Dew, Calypso, and Whisper, then third using the same gang, so I've got myself a Mega Delphox now and it accidentally became the highest level member of my team (I think @UnovanZorua's spirit popped into my switch and gave it ten M XP Candies). I beat the Rogue Megas (played "Fat" while battling Victreebell), and Dew evolved into Meganium, so now every member of my team can Mega except for Raichu. @Joeybear7 could anyone survive the Dauntless Raichu Duo without being level 100? Can I even MEET them before beating the game? Also, I found out my E battle was against Canari, which surprised me, because I thought it would be my C battle. So now I'm trying to gather ticket points so that Naveen will share his fanatic (sorry, Canatic) knowledge with me. Also, I hit like Rank T on the online battles. I usually get 2nd-3rd, but I get so many titles, like First Mega Evolver, Mega Defeater, etc. But there's always one guy in every battle who racks up like 7-13 points and destroys everybody…
Also, Zygarde gave me a pebble. The description is literally like "there is nothing interesting about this." He really does act like he only has a single brain cell. Then L showed up and was like "I am L." Me (looks up and down): "No kidding." XD

So Ansha and Hoopa can show up before you beat the main game of Z-A?