In a seasonal extension of the "Senior Dialect" post of a few months back, I shall here give a short description of how various Japanese dubs of Christmas related media adapt the linguistic traits of the (bloke in red).

It is etched in stone (according to my personal research, which may give the aforesaid utterance somewhat a pompously prodigious tone) that Santa Claus, Father Christmas or Saint Nicholas in all shapes and appearances shall use a thinly veiled Hiroshima dialect with the occasional archaisms as well as amiable colloquialism sprinkled in the evoke the impression of an ancient, but avuncular giver of gifts.

Thus, without further ado:

Arthur Christmas

In this animated fantasy-comedy, we have not only one, but an entire family of fellows in varying garbs of Yule nuances. Though two of them only possess the full beard to count as a proper Father Christmas, whereas the others are just becoming the bulging bloke.

The patriarch of the family, Grandsanta (voiced by Bill Nighy in the English version and Kenichi Ogata in the Japanese version - also the voice of the grandfather of one of the protagonists in Rockman Dash), rendered in the Japanese version as Ojiisanta (おじいサンタ, "Grandfather Santa"), speaks true to the Hiroshima dialect stereotype of the Senior Sociolect, as seen here where we also see the other Chrimasses in action:

"Grand Santa" Claus:
わしがサンタ!
Washi ga Santa!
"I am Santa Claus!"

Stephen Claus:
いや、僕がサンタです!
僕が先に取ったのに見苦しい‥
Iya, boku ga Santa desu!
Boku ga saki ni totta ni migurushii...
"No, I am Santa Clause.
Even if I took this first, it is unsightly of you..."

Malcolm Claus:
でも、現任のサンタ私だから。この駒、私が使う。
Demo, gennin no Santa watashi dakara, kono koma, watashi ga tsukau.
"However I am the one currently serving as Santa Claus. Thus, I shall use this piece.

Stephen Claus:
いいよ。只の名誉職なんだ、お父さんは!
Iiyo, tada no meiyoshoku nanda, otousan wa!
"That' all right. You are merely just an honorary member, Father!"

Malcolm Claus:
そうとも。名誉あるし事だ
Soutomo, meiyo arushi koto da
"Indeed! It is a most honourable thing"

"Grand Santa" Claus:
滅多坊で髭がじゃ。誰でも良いって事だよ。
Mettabou de hige ja. Dare demo ii tte koto dayo
"It's a reckless bloke with a beard. Anyone would do, I say!"

The 130 year old Grandsanta, grandfather of the family, uses washi as is expected from the Hiroshima dialect along with the copula ja (rather than the standard da), whereas his son Malcolm, the current Santa Claus, uses watashi, an aloof/proper-sounding pronoun for an adult in fiction that facilitates a professionalism and just maturity in his personality even if he is boastful. The eldest son Stephen, however, speaking in keigo (polite speech) uses boku, where one would expect him to use ore in informal speech. Arthur Claus, the youngest member of the family and hero of the story uses boku, as seen in this later scene:

クリスマが子供の物、僕には関係ない。
Kurisumasu ga kodomo no mono. Boku ni wa kankei nai.
"Christmas is a thing for children. I don't care about it."

The anime Santa Company, has a rather stylised version of Saint Nick called Nicholas White, we only briefly see him in the trailers, but this is enough to ascertain that he, too, is a speaker of the Hiroshima dialect, where he can be heard using onushi (おぬし), an old-fashioned pronoun elsewhere associated with samurai speech, that works as an kimi for the elderly.

The JRPG Seiken no Densetsu 2, in the west The Secret of Mana (released in the west to the SNES and in Japan to the Super Famicom; then later to modern consoles as a remake, which is the version that I am looking at here), features Santa Claus in two forms firstly as a demonic Jotun and the second as the plump man of pudding holidays, once freed from his curse, he replies:

おお、トニカイよ。心配かけてスマンかった……もう大丈夫じゃ。
ワシがフロストギガースだったんじゃよ……最近の子供たちは誰もワシのことを信じなくなった‥
マナが少しなくなると 子供たちでさえも夢や希望を失ってしまう……
もう一度 皆に取り戻してあげたくての。
マナの樹というのはあっという間に、大きく成長するそうじゃ。
巨大なクリスマスツリーを育てようとついマナの種子を、持って来てしもうたんじゃよ。
ところが、マナのエネルギーが ワシの体に影響してワシをあのようなバケモノに……
マナの力も使い方を間違えると とてもキケンなもんだったんじゃな!
君らにも迷惑をかけた! 火の種子を返そう。

Ō, tonikai yo. Shinpai kakete sumankatta…… mōdaijōbuja. Washi ga furosutogigāsudatta nja yo…… saikin no kodomo-tachi wa dare mo washi no koto o shinjinaku natta‥ Mana ga sukoshi nakunaru to kodomo-tachide sae mo yume ya kibō o ushinatte shimau…… mōichido mina ni torimodoshite agetakute no. Mana no ki to iu no wa attoiumani, ōkiku seichō suru sōja. Kyodaina kurisumasutsurī o sodateyou to tsui Mana no shushi o, motte kite shimouta nja yo. Tokoroga, Mana no enerugī ga washi no karada ni eikyō shite washi o a no yōna bakemono ni…… Mana no chikara mo tsukaikata o machigaeru to totemo kiken'na mondatta nja na! Kimi-ra ni mo meiwaku o kaketa! Hi no shushi o kaesou.

"Oh, my dear reindeer! I do apologise for worrying you. I am well now. I was the Frost Gigas, you know, children had recently stopped believing in me... And the mana as well as the dreams and hopes of children had decreased a bit. I wanted to return it all to them. The Tree of Mana had grown so suddenly and so large. I fetched a mana-seed so that I could grow a giant Christmas Tree, oh darn it. My body was influenced by the energy of the man and thus I had become that monster... I was quite wrong about how to handle mana, it is a dangerous thing, indeed! I am so sorry to have cause you this, dear children. Please, let me give you the Seed of Fire."
(Seiken Densetsu 2 [Playstation 4])

The jolly Nick uses washi, ja as well as a rare plural form of kimi, the informal second person pronoun that indicates familiarity, kimira, which gives it a old-fashioned feel to fit with his personality, hence my choice of "dear children" to reflect the avuncular tone.

In case you were curious about how Santa Claus looks when he is a Frost Gigas, have the classic Super Famicom sprite of him:

WRRAGGH! YE BETTER BE NICE, OR I SHALL EAT YOU, NAUGHTY CHILDREN!!

Who, as well, uses the Hiroshima dialect, albeit a bit more imperative in his ordering the player to "begone (立ち去れ, tachisare)" or "sod off," as old codgers are want to say in our day.