I go to this one league in which there's really not much competition and I want to lay off by not playing my blastoise keldeo, are there any fun decks out there that any of you know of?
Flygon/Dusknoir with or without energy is fun. Raticate is silly if you can magically make it set up. Scizor/Garbodor was fun for me for a while, and I'll be rebuilding because it isn't horrible against TDK. Boundaries Crossed and Next Destinies was good to "rogue". There's also Gardevoir/DarMAXitan, which was fun to play. Y'know, stuff like that.
Flareon/Cofagrigus is surprisingle very good, and rather fun to play. It's fun to watch a rondom smattering of pokemon go from "noob deck" to "OHKOing EXs every turn".
Gliscor/Garbodor is good fun. I used it on PTCGO for a while and it did me well.
Also Heatmor is great fun if you have the 40-50 Fire Energy necessary to build it
Mewtwo is the ideal starter. If Mewtwo gets knocked out by Deoxys or another Mewtwo, Toxicroak can come in and revenge. Virbank gym makes poison jab a viable attack (might as well throw in a few lasers too) and Bouffalant is never a bad attacker. EXP share helps to conserve energy. I play it online and while not top tier, it does well.
Another one is Garchomp/Altaria. It's not as good here as it was in Japan, but it's still a solid deck that can easily set up.
My friend has been testing Garchomp Altaria, and all he can manage to lose to is Blastoise/Keldeo, I could get you a nice list close to his if you'd like