Silvally is my favourite Pokemon, and it isn't close. I've been meaning to make a deck around it and its interesting type-shifing mechanic. But now I have!
Kabutops from 151 is the answer I've been looking for, as it's ability grants you a weakness enhancer without the need of a tool! At first I thought that Supereffective Glasses would do it, but then you wouldn't have the tool slot available to actually change the type lol. Anyways, Silvally GX being its own draw engine is really convinient, making it so you don't need a Bibarel sitting on the bench at all times, and the fossils Archeops and Kabutops provide your damage and energy acceleration. On its own, Silvally GX does 200 damage for 2 energy when hitting for quad weakness, but if you play a supporter card during that turn, you're hitting for 480! Don't have any supporter cards? Grant makes for an easy way to get one back when you need it. Even better if you're running a fighting-type Silvally GX! When not going against a weakness deck, just use the other memories as discard fodder for Grant and Ultra Ball. I'd also suggest playing as either the fighting or water type set so you can benefit from Grant or Wash Water Energy. Have fun!
(In case you can't tell, this was made to be usable within Live's current expanded format, so when suggesting, please keep them within the SM cards. Thanks!)