Today's CotD is Junk Arm from TM, probably the best Trainer to come out of the set. Being able to discard 2 cards from your hand alone is a very powerful effect for decks that rely on discard, and the fact you get a Trainer out of your discard just makes it even sweeter for any deck. Really, there's no downfalls with this card, it's usable in any deck, as the discard could be used to clean up room for Uxie to get the most from its Poke-Power, etc etc.
Modified - 10/10 (Really it's usable in any deck pretty much, who doesn't want to reuse cards like Luxury Ball, or grab stuff like Energy Gains and Power Sprays that have been used?)
Limited - 1/10 (Here's the problem...Junk Arm is the ONLY Trainer in the set besides the Alph Lithograph, so unless you're drafting several different sets together, don't bother. If you do the latter though and get any Trainers, run this)
Unlimited - 8/10 (Item Finder is superior, but this is still a great card to use here)