Disclaimer: I never got too into the whole Pokemon thing, so I took a bit of a different tack with it.
Panel 1: We see a referee in the middle of a dilapidated football stadium. A circle has been drawn, about 10 feet in radius, with a circle in the middle with a 1ft. radius. This would be where he's standing. At each side of him, we can see red/white pet carriers, one at each end of the circle. By each carrier, a trainer stands with 4 other carriers. The trainer on the right side of the panel is well-dressed, in black slacks, a maroon sport coat, and a white t-shirt. The other is a 15-year old in a baseball cap, ragged jeans, and a blue puffy vest. There's a crowd, but the stadium is still relatively empty. There are dark red stains on the ground, as this is not the first time this has been the stage for events like this.
REF: LET'S GET READY TO RUMMMMMMMBLE!
Panel 2: Another trainer stands by what would be the concessions stand, in a trancelike state. He has the same sport coat, slacks, and shirt as the trainer in panel 1, but he's considerably younger, and a baseball cap, with a stylized, cubistic rocket with its trail tracing a capital R on the front, shades his eyes. There's a small trail of blood coming from his nose, somewhat congealed. He has a carrier with him, the same color scheme as the carriers in the first panel, and it emits a light mauve glow.
MYSTERIOUS TRAINER(SPEECH BUBBLE BACKGROUND LIGHT MAUVE, TEXT AND BORDER DARK PURPLE): WE'RE LATE.
Panel 3: Close on the front of the carrier. The interior is darkened, but we can see a pair of light mauve hands grasping the bars, almost human, but not quite. A pair of eyes glows from the darkness, in the same light mauve. There is a metal plate on the front of the carrier, below the eyes but above the hands, bearing only the greek letter μ.
MYSTERIOUS TRAINER(OFF-PANEL; SPEECH BUBBLE BACKGROUND LIGHT MAUVE, TEXT AND BORDER DARK PURPLE): NO MATTER. WE'LL HAVE OUR CHANCE.