Gideon's second ability causes him to become a creature with the creature types Human and Soldier. He remains a planeswalker with the planeswalker type Gideon. (He also retains any other card types or subtypes he may have had.) Each subtype is correlated to the proper card type: planeswalker is only a type (not a creature type), and Human and Soldier are just creature types (not planeswalker types).
Gideon, Martial Paragon
Gideon's second ability doesn't count as a creature entering the battlefield. Gideon was already on the battlefield; he only changed his types.
The set of creatures affected by Gideon's first and third abilities is determined as the abilities resolve. Creatures you begin to control later in the turn and permanents you control that become creatures later in the turn won't get +1/+1 or +2/+2.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Daarken
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
