The new summons, or as they are called now "familiars" (pokemons) are just skins.
They are one of the final rewards from the new A Pirate's Tail Quest.
There's 1 new for each vocation.
From wiki:
The new “Pokemon’s” as you called are new “summons” ( professionally called familiars) which are associated and allocated for each vocations. They provide only esthetic comfort for the eye ( they are new skin/ outfit for your summon) and are obtainable by completing A Pirate's Tail Quest. They do not change mechanics of your summon ( increase/ decrease/ change spells or behaviour)
More details:
TibiaQa- https://www.tibiaqa.com/20826/what-kind-of-familiars-can-be-summoned-by-each-vocation
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