You can Special Summon this card (from your hand) by returning 1 "U.A." monster you control to the hand, except "U.A. Mighty Slugger". You can only Special Summon "U.A. Mighty Slugger" once per turn this way. If this card attacks, your opponent cannot activate cards or effects until the end of the Damage Step.
http://yugioh.wikia.com/wiki/U.A._Mighty_Slugger
You can Special Summon this card (from your hand) by returning 1 "U.A." monster you control to the hand, except "U.A. Perfect Ace". You can only Special Summon "U.A. Perfect Ace" once per turn this way. Once per turn, during your opponent's turn, when a card or effect is activated: You can discard 1 card; negate that activation, and if you do, destroy it (this is a Quick Effect).
http://yugioh.wikia.com/wiki/U.A._Perfect_Ace
If a "U.A." monster is Normal Summoned to your side of the field: You can add 1 "U.A." monster from your Deck to your hand. Once per turn, if a "U.A." monster(s) is Special Summoned to your side of the field: All monsters you currently control gain 500 ATK.
http://yugioh.wikia.com/wiki/U.A._Stadium
Umm.. dunno, might be decent?