I know this is for single RMTs, but I've come up with a variation on Arcanine that basically gives me two on my team, but it requires another Pokémon to do it so they come as a combo. I'm hoping that this is an effective way of getting Arcanine as much time in the ring to do his thing.
@ Life Orb
EVs: 80 HP / 252 Atk / 176 Spe
Nature: Adamant (+Atk, -SpA)
- Flare Blitz
- Wild Charge
Arcanine is my favourite Pokémon, so I'm always going to have him in my team. It's a pretty standard Arcanine I guess, but with a twist. Flare Blitz is the STAB move, Wild Charge covers the weakness to Water, Retaliate (& therefore, the lack of Extremespeed in this set) will be explained below, & Crunch is really just to fill the 4th spot. Ghost & Psychic types are always a pain. The EVs & Nature are there just to boost it's quick attacking prowess, the Life Orb gives him the obvious extra attacking power, & Intimidate let's him perhaps get an extra turn to do his thing. He's basically a kamikaze fighter, getting in as much damage as possible as soon as possible. Once he's down to low life, I'll switch him out with…
EVs: 252 HP / 4 SpA / 252 Spe
Nature: Timid (+Spe, -Atk)
- Dragon Pulse
- Calm Mind
- Healing Wish
Again, another (mostly) standard set with a twist. When Latias is switched in, my tactic will basically be to boost my Special stats with Calm Mind, & Recover when necessary to make her a tank with the ability to punch big holes in teams with Dragon Pulse STAB. The HP Evs are there to give her as much HP to withstand the hits to get her to that stage where she can start using Dragon Pulse to sweep opponents. With the Leftovers, it should make her a complete pain to KO. Here's where the whole point of this tag team comes in: When I feel Latias hasn't got much left in her, I use Healing Wish to bring Arcanine back into the game on the next turn, rejuvenated & ready to fight like brand new. The EVs in Speed coupled with her base 110 Speed stat should get the Healing Wish in before she can be KO'd more often than not.
Then, on Arcanine's first turn back into the game, I use Retaliate (which gets the 100% power boost from the first turn) as a super-powered Extremespeed. I know Retaliate doesn't have the speed priority that Extremespeed has, but Arcanine is pretty fast to begin with so I'm hoping, more often than not, he'll be able to get it in first & do significant, if not fatal, damage to the opponent. After the first turn, Retaliate hasn't got much use because of that lack of a speed priority, but it's base power is only 10 less than Extremespeed so it's there as a you-never-know sort of move.
Then after that first turn back into the game, Arcanine can start sweeping opponents again in typical fashion. Used correctly, this tag team essentially gives me 7 Pokémon on my team, & it lets me use my favourite & most offensive team member twice. I could even take this further & have my whole team as Arcanine & 5 speedy yet offensive Healing Wishers, so that in between Arcanine I still have an offensive threat, & when my Pokémon is about to be knocked out, I use Healing Wish & bring Arcanine back to life. After Latias, there's aren't many speedy Healing Wishers I could use, but Celebi, Jirachi, Lopunny & Shaymin could all fill that role. Using all 5 of those Pokémon alongside Arcanine, it basically giving me 11 team members thanks to Healing Wish.
I have no idea if this has been thought of before, or how effective is really is (I know a fair deal about the competitive scene, but I'm no expert), but I haven't seen anyone try this before anywhere so I'm hoping I'm onto something. Constructive criticism is more than welcome, I want to get the most out of Arcanine that I possibly can!