Updated.
Forgot on Saturday because of some issues. Okay, so, if you claimed a Pokemon, and you did not get added, like the situation with Raichu, it's because of two reasons:
1.) It was already TAKEN along time ago and no more claims can be made
2.) It didn't say "TAKEN" when requested, but if someone claims a Pokemon before you do, they are put their instead of you because their post was first.
The Raichu situation was #2.
I'll try to update at least twice a month since school is starting soon.