This Beast truly is relentless
You can load them up with counters, double those counters with things like Vorinclex, Monstrous Raider, slap on some equipment like Sword of Fire and Ice, or enchant your unblockable creatures with Eldrazi Conscription and the like
We can also be evil and poison kill with Corrupted Conscience
Tokyo is unapologetically overwhelming on a first visit, so it helps to begin with a clear focus on where you want to go
Interest in the game inevitably leads to interest in leagues, tournaments, etc
So, the best-case scenario lets Mega Slowbro EX unleash a jaw-dropping 270 DMG on the entire battle arrangement of the opponent (90 DMG to the Active Spot and 60 DMG to each of the three Benched Pokmon)