Accumula Town is basic with a Pokémon Center, residence, and a population.
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{ Accumula Town }
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Prof. Juniper is standing outside the Pokemon Center;
go talk to her and she'll lead you inside and show
you around. Heal your Pokemon (you're forced to) and
let her show you around some more, then you'll be
able to exit. I'd recommend saving first, though.
Going outside, you'll see some people moving towards
a crowd to the left. Follow them to enter the crowd
yourself with Cheren and then you get to see a speech
from the evil team of Black and White, Team Plasma.
Once he leaves with his group of grunts, the crowd
will dissipate, leaving you, Cheren and one other
person behind. This person will come to you and
introduce himself as "N", then challenge you to a
fight.
<--------->
{ Battles }
<--------->
<--->
{ N }
<--->
<---------------->
{ Purrloin LvL:7}
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N will leave after the fight, then after some more
talking Cheren will too and we've finally got the run
of the place at last. I would start by healing your
starter; just go back in the Pokemon Center and do so.
Bianca will have somehow snuck out of there without
being seen by you; I do love how every NPC in Pokemon
is capable of teleportation!
Outside the Pokemon Center, go to the top left house
in the city, go upstairs and talk to the guy to
receive a Poke Ball. Exit that house and then go to
the one in the top right; you'll be able to oversee
Route 2 as you go there.
That's all Accumula Town offers, so head left out of
the town, into Route 2.