Every player must fight every other player, but they can do so in whatever order they please. Only pokefusions may fight: unfused pokemon are not eligible.
STEP 1 CHALLENGE
For a bout to occur, a player must challenge another player. A player can either accept the challenge, or pay a bounty of 25x[[wins]+1] to decline. A player has a chance to sell their pokemon or pokefusions before declining. It becomes more expensive to decline the more matches a player has won.
STEP 2 SELECTION
The players then choose which pokefusion will be fighting. If they both only have one valid pokefusion, this step is skipped and we head straight to...
STEP 3 BATTLE
Each player attacks (the order is whoever posts first). If a player has more than one attack type, they chose which will be attacking (e.g. if a player was using a Pidslash (Pidgey/Sandslash), a Pidgey can attack with either normal or flying. If players describe how their pokefusion fights, they'll gain +1 to their fan roll after the fight.
[SUB-STEP: any time before step 4, any player may place a bet if they have the money for it. A player in a fight cannot bet on their opponent winning. See Gambling below.]
STEP 4 RESOLUTION
The battle is decided by opposing d6 rolls. Elemental weaknesses and strengths half or double the rolls, if the defense has two elements they're both taken into account.
Consult the Gen 1 type chart.(e.g. fire attack vs water defense would half the roll; water vs. rock/ground would x4 the roll)
After the roll, any additional bonuses are taken into account:
Traits: some personalities add bonuses
Evolution: an evolved attack or defense adds +1 for each evolution level (i.e. Charmeleon is +1, Charizard +2) to that attack or defense (i.e. Ponyizard would only gain +3 to defense, not attack).
In case of a tie, whomever has the most fans win. If both players have the same number of fans, it comes down to a 50/50 flip. There are no draws.
The winner gains $100, the loser gains $50. If someone won their bet, they receive their winnings.
Each player then gains (or loses) fans for their performance, using the formula:
If won: +1d6 fans. If lost +1d6-3 fans.
Then, +1 fan if you described how your pokemon attacked (just naming a move isn't enough, but you don't have to write pages, a short description is enough, like "A beam of water splurts out the crystal that makes up Starmer's face!").
You can never have negative fans. Other factors (like traits and rare pokemon) can gain fans.
EXAMPLE
EXPLORER PENNY challenges RESEARCH MARVIN to a battle.
Marvin: I accept! Bulbmander, I choose you!
Penny: Squirtmeleon, I choose you! Squirtmeleon, use Bubble Beam!
Marvin: Bulbmander, use Vine Whip!
NQT: Squirtmeleon's water attack vs Bulbmander's fire defense: roll 2(x2 for weakness) = 4!
Bulbmander's grass attack vs Squirtmeleon's fire defense: roll 6 (/2 for strength) - 1 (evolved defense) = 2!
Squirtmeleon defeats Bulbmander, Explorer Penny is victorious!