R/S -> D/P [DS Lite]
D/P -> B/W [DS Lite + 3DS]
B/W -> X/Y [???]
I don't see a problem. If you can play the game, you can trade it (provided you aren't playing on a Gameboy). Nintendo isn't excluding anyone they haven't already left behind.
EDIT: You can trade from Gen III to Gen IV even...
Scizor that looks similar to but plays quite differently than Tomohawk's set
Also reserving OU Porygon-Z analysis when either Breloom / Scizor are done with QC
EDIT: Taking Claydol OU too, I'll start writing these two up today and tomorrow