Her first Pokemon is Spiritomb, a ghost- and dark-type. This thing doesn't hit terribly hard, though it can get really annoying thanks to its high defenses, lack of weaknesses and Will-O-Wisp for burning your party members. Use your highest power moves to take it out in a hurry - the dragon-type Outrage typically works quite well used several turns in succession.
Second is Milotic, a water-type. Pumped to the brim with harsh attacks - no less than Hydro Pump, Blizzard, Dragon Tail and Bulldoze - Milotic can plow through your whole team if you're not carefully. It's best to either paralyze Milotic or put it to sleep, then blast it with electricity. Physical attacks work better than special thanks to its stats.
Third is usually Garchomp, a dragon- and ground-type, depending on your Pokemon deployment. This thing is Cynthia's strongest Pokemon by far and, like Milotic, will absolutely trash your team if you're not careful. It's both strong and fast, and requires a solid hit from an ice-type to go down easily. Dragon-types can try to take it on, but they'll probably die first thanks to Garchomp's superior speed. Anything that uses Fly or Bounce will probably have an easier time with Garchomp since they'll be beyond its line of sight, as will any Pokemon that can paralyze it or put it to sleep.
Fourth is Eelektross, an electric-type. Fortunately this Pokemon is probably Cynthia's easiest offering, as it's more defensive than offensive. Finish it off with any strong attack move that's not ground-based, as its Levitate ability makes Earthquake, Dig and the like miss. You may want to use this match to beef up in preparation for other, more difficult matches.
Fifth is Braviary, a normal- and flying-type. Hits hard and fast, but is otherwise fairly unremarkable. Smack Braviary down with swift use of an electric- or rock-type move.
Last is Lucario, a fighting- and steel-type. This potent Pokemon is as physically strong as Garchomp, but it lacks the same amount of speed. Consequently it can be wiped out rather easily with a strong fire-type attack. Though it has several powerful attacks, the only one to really fear is ExtremeSpeed, which it will use on any Pokemon that are weakened in its presence. If your Lucario killed is weak, pull it out, use your next turn to heal it, then put it back in when your current Pokemon faints under Lucario's attacks.
First is Spiritomb, so Musharna wont work or Breloom. I would recommend Kyurem because it is in the Giant chasm and has 130 base stats for offense. Tran it really good, and you could beat Cynthia easily.
Your first challenge is an Accelgor. This speedy creature is probably Alder's easiest Pokemon, and only presents a challenge in that it's fast and will get the first attack off. A fire- or flying-type Pokemon will have no trouble beating this thing down in a hurry.
Second is a Bouffalant. Though a bit slow, this big guy hits really, really hard with its Head Charge – which it generally uses over all else – and can knock your Pokemon out easily in one hit. That said, it hurts itself with Head Charge, so if you can deliver a hard fighting-type blow that doesn't quite knock it out, Bouffalant will probably finish the job on itself. You'll lose a Pokemon, but this is a small price to pay to avoid its other attacks.
Third is a Druddigon. This is possibly Alder's strongest Pokemon, as it's got a high attack stat and is only weak to dragon- and ice-type attacks. If you've got a special-based ice-type Pokemon then this is a piece of cake; if you've got a dragon-type it's only tough if Druddigon goes first – if neither ... you're in trouble. Ideally, you'll want to debilitate the Druddigon (sleep is best) then hit it with your best attacks until it goes down. A Double Team and Toxic combination can also work wonders.
Fourth is a Vanilluxe. If you have a fast first-type this thing goes down in an instant. If not you'll face a potentially long battle, for if you're not vulnerable to ice- or steel-type attacks it will sit and use Light Screen and Acid Armor on itself over and over. Not difficult in and of itself, but its penchant for draining your attacks can be a nuisance.
Fifth is an Escavalier. Fire-type users can blow this bug- and steel-type away in an instant. Others will have a tougher time, though ground-, rock-, and even water-type attacks can bring it down with a bit of time. Keep psychic-types out of this fight at all costs.
Last is Alder's star Pokemon, a Volcarona. This big insect is a mixed fire- and bug-type with some hideously powerful attacks, but one big weakness: it's not that fast. If you've got a flying-type that's reasonably speedy, like a plain old Unfezant, you can knock Volcarona out in a single hit. Water is good, too, though many water-types won't be quite fast enough to keep Volcarona from going first, which is a bad idea since it has Hyper Beam.
I would recommend a bulky rock type Pokemon for Alder, as it has a type advantage for half of his team. He isn
t very effective against a fast steel type like Cobalion until the Volcarona, though he has coverage on his Bouffalant and his Accelgor. But luckily, Cobalion is pretty decent in speed. I would say you need a fire and fighting type for his first two Pokemon. But he hasnt got a pseudo legendary, but a strong near legendary as showing in Volcarona.
Sorry about the green text. But hope this helps.