I am 99% sure the answer is no. Just as they don't earn EXP, I believe that your pokemon's experience-type stats (EXP and EVs, which are both earned by beating opposing pokemon) are frozen while you're in either the Battle Tower or the Battle Frontier.
Unless you get Exp in FRLG Trainer Tower (I don't remember right now - but I do know you can use items in there) you wouldn't get EVs there either. As a side note, you also won't get seen pokemon added to your dex.
_________________Need homework help? "Screw the Ivys, I'm applying to Smogon University!"ShiniesRuby:
Spinda, Golbat, DuskullPearl:
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