I have checked the full list of glitches in generation 5 on bulbapedia and these aren't on there:
When on random match up, on any mode ( I think ) and you have selected free, and a mini profile of you is on the touch screen, on the top screen, it says receiving data for a few seconds, then says searching for your opponent. If you tap the touch screen while it says receiving data, a message comes up that says an error occoured. Then you press A and it goes again from receiving data. I don't see how tapping the touch screen is an error, so this may be a glitch.
When you are on GTS and you offer a Pokemon, and it shows it's animated sprite and says " ........ will be sent to GTS" or whatever, and they fly away in a pokeball, once when I did it with a breeded Tepig, it showed the back sprite instead. With every other Pokemon I've done it with, it shows the front sprite. This may also be a glitch.
They aren't dangerous because nothing has happened to my game that is odd.
So are these glitches? Are they intended? Are they already discovered? Do they work with you?
EDIT: Now that WiFi for gen 4-5 has closed (I think) this no longer happenes, so there is no point in this question now.