Froslass is a potentially underrated tech for situations like elekid just described, although there are a number of issues with it, including Unown G and Warp Point as well as the energy loss you'll take every time you switch back and forth between Froslass and Gallade
Luxray GL lv. X is a better, easier answer to Nidoqueen, and aside from that, it is just an all-around amazing card that gives any deck it is included in a brutal edge against virtually every single deck in the format. To get rid of Nidoqueen in one hit, Lucario is going to be necessary, and its inclusion along with Luxray aids in the Kingdra match-up as well, which is always nice. Kingdra is otherwise going to be problematic since it has such high HP, usually runs Super Scoop Up and/or Floatzel GL lv. X, swarms and recovers easily, etc..
To the OP: I don't know if your brother is going to continue the Gallade experiments, but I'm bent on working through this card's weaknesses (Nidoqueen, Power Spray) and coming up with something viable.