I remember my first PVP battle on Diamond where I just barely won against my friend Patrick by the skin of my teeth in a double battle match. Long story short it went down to his Giratina against my Heatran, his Giratina took a Lava Plume hit from Heatran earlier on before it KO'd my Dialga with Dragon Claw, thankfully I was able to get Giratina in the red with Dragon Claw before my Dialga fainted as my Heatran was hit with an Earth Power from the Giratina just barely avoiding a OHKO due to the burn. I finished it off with another Lava Plume and sealed my victory after a grueling bout.
Patrick's team was Giratina, Dialga, Empoleon, and Infernape.
My team was Torterra, Staraptor, Dialga, and Heatran.
Easily one of my closest matches by far. Also another match where I swept through my opponent's Groudon, Kyogre, Giratina, and Heatran with a LO Giratina. I'm dead serious when I say that lol.