This card is used in decks which might need important cards out of their Prizes before they're able to take them naturally from KOs. This includes:
Ethan's Typhlosion needing Ethan's Adventure
Control/stall/mill decks, which don't take Prizes
It can also be used with Ciphermaniac's Codebreaking to set up Chansey in a known location in the Prizes.
On PTCGL, when you play Redeemable Ticket, the top card of your deck becomes your new Prize 1, the next card down becomes Prize 2, and so on. The numbering before you played Redeemable Ticket is forgotten. (So if you took Prizes 1 and 3 earlier, leaving Prizes 2, 4, 5, 6, then played Redeemable Ticket, your new Prizes would be labeled 1, 2, 3, 4.)
This defends against several attacks:
Technical Machine: Devolution
Dragapult ex's Phantom Dive (only the Bench snipe)
Sylveon ex's Angelite
Roaring Moon ex's Frenzied Gouging
Any retreat-locking attack
Mist Energy is useful for decks that play Pidgeot ex. Blocking TM: Devolution protects your search engine, and Pidgey is vulnerable to Phantom Dive snipes as it only has 60 HP.
Mist Energy is also used frequently in wall decks to further reduce the number of opponent's outs. Other than Milotic ex, walls only prevent damage. Mist Energy covers effects for them.
This card has specific uses in a few decks:
In Archaludon ex, it lets Archaludon ex use Raging Hammer, which can end up hitting for more damage than Metal Defender. Sometimes it's combined with Brute Bonnet's Poison to rack up damage counters on Archaludon ex and strengthen Raging Hammer.
In Feraligatr, it lets Feraligatr use Reverse Thrust so it can switch to a wall and hide on the Bench during the opponent's turn, or Big Bite to trap the opponent's Active.
In Pidgeot Control, it lets Garganacl use Corner to trap opposing Pokémon.
These are used in control/stall/mill decks to force the opponent to Bench liabilities, which you can then trap.
When playing against these, try to use cards that discard as costs (e.g. Ultra Ball) to dump Flute/Erika fodder into your discard pile.