Alternatively, after using "Tour Guide's" effect, you can return her back to the hand with a card like "Compulsory Evacuation Device", and overlay this card and the remaining monster for a powerful Xyz such as "Number 17: Leviathan Dragon". This way, you'll be able to use the effect of "Tour Guide" again for another Rank 3 Xyz on a future turn.
In an Agent deck, you can Normal Summon "The Agent of Creation - Venus" onto the field and then Special Summon this card from your hand. Use "Venus's" effect to Special Summon 2-3 "Mystical Shine Balls" from your deck to the field. You can then Xyz Summon both a Rank 2 and a Rank 3 Xyz in one turn.
Normal Summon "Wind-Up Hunter" and Special Summon this card. Overlay the two for "Wind-Up Carrier Zenmaity". Detach "Hunter" to Special Summon "Wind-Up Rat". Use "Rat" to revive "Hunter". Tribute "Zenmaity" for the effect of "Hunter", sending 1 card from your opponent's hand to the Graveyard. Overlay for another "Zenmaity" and repeat. In this way, you can deplete half of your opponent's hand on your first turn.