The double-peace/victory signs I don't think are necessarily specific to any one anime. It's a pretty common gesture. Raph's clone technique is of course highly reminiscent of the Shadow Clone Jutsu technique in Naruto, especially how the protagonist himself uses it (and his finishing strike from below seems very similar to Naruto's sneak attack on Neji in the Chunin Exams). I feel like some of Leo's sword techniques are things I should recognize, but a specific reference isn't coming to mind. Sword in the mouth might be Zoro from One Piece.
As for the drill thing, I think possibly we're one degree of separation from Gurren Lagann. Drill on the end of a giant hammer, in particular, was done at the end of Mahou Shoujo Lyrical Nanoha: StrikerS, executed by Vita and her hammer weapon, Graf Eisen. But that was likely a Gurren Lagann reference, because Graf Eisen was voiced by Tetsuya Kakihara aka Simon from GL.
April's sequence felt very reminiscent of the "Worthy" Cap scene from Avengers: Endgame, constantly bouncing her weapon around to attack rapidly and from unpredictable angles.
 Watched a longer video of the full fight, and there's definitely more Gurren Lagann there. Hamato Yoshi throws a punch very reminiscent of "let me see you grit those teeth", and Shredder puts up a multi-drill defense against the final attack that's very similar to the final fencing match between the Tengen Toppa Gurren Lagann and the Granzamboa.
Edited by mx-01 archon, 16 September 2020 - 02:50 AM.